WK2 Jeep Grand Cherokee

Technical Information to assist other WK2 Jeep Grand Cherokee owners

Information Includes:
About Tyres & Wheels, Tyre Pressures, Fitting LT Tyres, TPMS, Snorkels, Lift Kits, Bull Bars, Head Light Adjustment, Towing, Vehicle Loading, Nivomat Shock Absorbers, Steel Suspension, Transmission Temperature, Variable Voltage Alternators, Oil Change & Reset, LED Driving Lights & Light Bars, Fuel Filters, Diesel Particulate Filters, CCV, Oil Catch Can, Glow Plugs, Power Performance Chips, Airbags & Load Assist Kits, LLAM Height Controller, Manual Park Release, Maintenance, Service Bulletins, Electrical Wiring, Fuses & Diagram, Auxiliary Fuel Tanks, Dual Battery, Charging Systems, Diagnostic Trouble Codes, Diesel Hydrolock, Roof Racks, Rock Rails & Sliders, Spare Tyre Carrier, Parking Sensors & Camera, Trim Removal



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Technical Information
    While this site is mainly for the 3ltr diesel with steel suspension, other information is useful to all models

Important: 2015 - 2017 WK2 owners & potential buyer
beware:

MA and MC classification: What you need to know
Update: FCA have had a change of heart and WK2 4x4s from 30 Mar 2017 on are now complianced MC


Some of these are PDF files so download Adobe PDF Reader if not installed


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Jeep Accessories
These are not advertisements.  I don't preference or recommend one over another and it's not a definitive list.
Jeep OE Accessories
Murchison Products
Dobinson Springs
Outback Armour
Jeep City

The Jeep Grand Cherokee VM 3.0L Diesel Engine

Interestingly the 3.0L diesel engine never was intended for Chrysler or Fiat products but the GM European market Cadillac CTS.



How Jeep ended up with a GM diesel

Tow Bar Safety Recall  U35 March 2018


STOP TOWING IMMEDIATELY IF YOU HAVE ONE  OF THESE TOW BARS UNTIL FIXED BY A JEEP DEALER

The affected Mopar Tow Bars installed since 31 May 2017 potentially pose an accident risk

LA82210140  LA82210141

Roof Loading

Beware of exceeding the 68kg roof loading...There is at least one case where the roof has cracked due to flexing on rough corrugated roads.
This can be an expensive exercise requiring removal of air bags & roof lining to repair cracks
See Roof Flex Video

Some Potential Problems

Coolant seepage at EGR hose  TSB: NUMBER: 07-004-13
This bulletin involves replacing the EGR hose.

Oil Change Indicator

The 2014 Grand Cherokees Powertrain Control Module (PCM) monitors operating conditions since the last service reset,  The engine oil change indicator system is duty cycle based, which means the engine oil change interval can be well before the scheduled maintenance interval.  If severe operating conditions are detected, the  PCM signals  the )  to display a flashing text message to change oil;  the vehicle should  then be serviced as soon a possible. Unless reset, this message will  continued to be displayed each time the ignition is switched to ON/RUN.  If operating conditions are determined  by the PCM to be normal, then the vehicle's scheduled maintenance interval is in effect..
 
Note:
  1. It is important to always change engine oil and filters when prompted by the "Oil Change Required" message or as per the vehicle's maintenance schedule. Under no circumstances should oil change intervals exceed  the maintenance schedule time or kilometers. Refer to your Owner's Manual
  2. To reset the EVIC  Oil Life %  back to 100% - turn on the ignition without starting the engine (foot off the brake) now press the accelerator fully down 5 times in quick succession...The Oil % should now reset to 100%
Warning:

Before checking the engine oil level turn the engine off and wait 15 minutes for the oil to return to the oil pan.
Any time the oil is drained and filled it is critical to wait 15 minutes before starting the engine.

Note:

It may take 30 minutes or longer for the engine oil in the oil filter housing to completely drain back into the engine. The oil will only drain back into the engine through the oil pump gears. When servicing the oil filter  residual oil in the housing may spill from the housing when the new filter is installed.

From www.wk2jeeps.com: Engine Oil and Filters 
 
Diagnostic Trouble Codes

Fault Diagnostic Trouble Codes (DTC) can be retrieved and reset by scanning your vehicle's fault log with a suitable scan tool like the Dash Hawk, UltraGauge or similar. Various inexpensive  Smartphone Bluetooth OBD2 diagnostic tools can be found online also or Torque ODB2 and downloading  the free Torque App for Android.  See: OBD2 Bluetooth Adapter with Torque Pro App and  How to install on Android.  For the iPhone/IPod/iPad some Bluetooth devices are not fully compatible with iOS devices in which case ELM327 WiFi OBD2 Scan Tool  or similar with a suitable WiFi specific app can be used e.g.  Engine Link & OBD Fusion  or the free version. Note also, some iPhone free OBD2 apps only work with specific branded OBD2 adapters so check first.  See: How to read OBD2 Codes with an iPhone.  


The 5 digit DTC Format

Jeep Check Engine Codes
Complete OBD-II Codes List
Chrysler Jeep Trouble Codes
Find Diagnostic Trouble Codes

How to stop a runaway diesel

Some diesels engines can suffer from what is known as "Diesel Runaway" where releasing the accelerator or turning the engine off fails to slow or shutdown the engine and it reaches or exceeds the RPM redline. If this occurs when mobile then  life and limb can be at serious risk; so how do you stop a diesel that does??...If moving, select neutral and bring the vehicle to a stop where safe to do so. When stationary, cut off engine fuel supply or air supply if possible or alternatively use a CO2 fire extinguisher and discharge it into the engine air intake.....Another cause can be engine oil getting to into the combustion chamber via faulty turbo seals and the engine runs on this oil rather than its diesel fuel; in this case restricting air supply is the only solution...All vehicles should carry a CO2 extinguisher so if you don't have one regardless of petrol or diesel, it's good advice to  have one
in your vehicle for off road use where grass or debris can build up around hot exhausts components with the potential of causing a serious fire....Also valuable if you do experience engine runaway with the engine over revving and in danger of destroying itself and seriously injuring you or bystanders.

Diesel Engine Runaway Video
Stopping Runaway Diesels

Water Crossing, Stalled or Hydrolocked Engine??

Under no circumstances try to restart the engine. Check that the engine will turn using the fan belt or a socket spanner fitted to the nut on the front crankshaft pulley. If the engine still won't turn, the chances are you have water in the cylinders. Since water doesn't compress, a Hydrolock (hydrostatic lock) has  occurred .


What To Do

Do you need to replace your glow plugs??

Experiencing difficulty starting your CRD in cold weather?  The problem most likely will be malfunctioning glow plugs or the glow plug control module which controls glow plug temperatures. In warm and dry weather, the diesel engine will start even if one glow plug is defective and all other plugs preheat. Apart from difficult starting and knocking during start, faulty glow plugs or control module will  log OBD fault codes (DTC) and can inhibit DPF active regeneration.

From: All About Glow Plugs  (Beru )

"Knocking during cold-start of a diesel engine is caused by an increased ignition delay when the engine is cold. The fuel ignites all of a sudden and the engine knocks. pre-heating and post- heating of glow plugs ensure that the engine reaches the operating temperature quicker. This preserves the engine, results in a quieter engine running and prevents knocking. The fuel will then be burnt more evenly and more completely. More energy is thus released and the combustion chamber temperature will increase quicker."

To test the glow plugs, measure each plug to ground  (multimeter on resistance) which should read in the order of .7 to 1.3 ohms.
If all test ok then check and  replace the glow plug control module if faulty.  Glow plugs are also very sensitive to voltage drop in the wiring
system which may require replacement.  Some suggest battery load testing first before replacing glow plugs.


Warning:  

To avoid irreparable damage, do not test the glow plugs with a 12 Volt source under any circumstance

Note:

Cover the glow plug thread with a recommended anti-seize grease before fitting to enable easier removal and prevent corrosion

Diesel Particulate Filters

Regeneration (I think)

Where exhaust temperatures necessary for regeneration are high enough Passive Regeneration of Diesel Particulate Filters (DPF) normally takes place automatically if the vehicle is used for  medium to long journeys or driven hard. If the PCM detects that the vehicle is being driven in a way that passive regeneration is ineffective or higher than normal exhaust back-pressure is detected, an active regeneration cycle is initiated by in-cylinder post injection or direct injection of fuel into the exhaust stream to raise the temperature of the filter to around 600Cto oxidise the Particulate Matter (PM) build up. Driving conditions such as long down-hill descents, city driving and frequent short trips, may not produced sufficient heat to fully oxidised all accumulated PM.  If  45% restricted (depends on the vehicle) or more then active regeneration starts and the engine management system  increases exhaust temp by various means including engine timing & high fuel injection to burn out the PM. This can happen as often a 400km..A message is sometimes displayed indicating the burn out progress..You can often smell or see a puff of white exhaust smoke as the PM burns.

 If all regeration attempts fail to clear the DPF,  PM will eventually accumulate to a point where the vehicle will go into limp mode to prevent engine damage. Immediate service by your Jeep dealer is now essential to diagnose the cause (could be a sensor) and may require forced regeration (limited number of times) or DPF replacement.

DPF technology is not that good for short start stop driving like city traffic or very short runs where passive regeneration isn't effective. If mostly city driving then where possible keep the revs up (probably on hills) for several km to raise exhaust temp (around 600C) or travel about 20mins above 60km/h usually does it.

Best use high cetane rating diesel fuel and not the lower cetane used by trucks. The quality of the fuel & driving style will determine the number of regenerations.

Warning!

Do not park or operate your vehicle in areas where your exhaust system can contact anything that can burn. A hot exhaust system can start a fire if flammable material such as grass or leaves comes into contact with your exhaust system. 


Closed Crankcase Ventilation Filters

Why?:

In a Closed Crankcase Ventilation system (CCV) ,The crankcase blow-by gases via the Positive Crankcase Ventilation valve (PCV) are routed into the intake manifold and then carried with the fuel/air mixture into the combustion chamber where it is burned. In a turbo charged engine, all blow-by gases pass through the turbo (and intercooler system if intercooled) before entering the combustion chamber. Because turbos operate at high temperatures, any oil in these gases results in carbon deposit build up which eventually reduces overall efficiency. Oil vapour in blow-by gases can be caused by incorrect engine oil and other factors like blocked air filters , leaking O-ring seals and worn (old) engines.

Fuel Water Filters

Why?:

Water in diesel fuel can cause major damage to your engine and fuel system (expensive) which is not covered by your vehicle's warranty or by   most insurances.  When remote touring, refuelling with water contaminated fuel is an ever-present issue; damage from which can be avoided by installation of a quality brand fuel water separator filtration system.  Most fuel water filters have a visual LED and audible alarm  in the cabin as a warning that the filter is approaching full and must be drained ASAP. Visual inspection of the filter bowl on a regular basis is good practice

About Fuel Water Separator Filters
Diesel Care - Fuel Manager Filters
Responsive Engineering - Water Watch


Quick Reference Metric Fuel Usage Chart

Unfortunately the new Trailhawk rather than show average fuel usage as litres/100km does so as km/litre.  This chart maybe handy when driving rather than doing quick conversions on the fly.


(Rounded to 1 decimal place)

Printable Copy

WK2 Transmissions


Years Model Engines
2011 - 2013 W5A580 5-speed automatic   3.0, 3.6 L
2012 - 2013   6.4 L
2011 545RFE  5-speed automatic   5.7 L
2012 - 2013 65RFE    6-speed automatic
2014 - on 845RE    8-speed automatic   3.6 L
2014 - on 8HP70    8-speed automatic   3.0, 5.7, 6.4L

Chrysler Group LLC initially received the 8HP 8-speed automatic transmissions from the ZF Getriebe GmbH plant in Saarbrucken, Germany which they now produce under licence in the USA at the 845RE & 8HP70 variants for the MY14 Jeep WK2 Grand Cherokee

About the ZF 8HP eight speed automatic transmission

Transmission Temperature

What should your transmission temperatures be under various driving conditions ?? This is not that easy to find exact information on. Running temperatures are heavily dependent on speed, loads and ambient temperatures but as a general guide for the 2014 WK2 3L CRD then:

Driving Conditions Temp (C) Comments
  Highway Driving     87 - 90  Depends on speed (* @ 27C ambient)
  City Traffic     86 - 89  Depends on stop/start (* @ 27C ambient)
  Optimum     88 - 89  Constant unloaded driving after warm up (*)
  Warm Up Highway      89   Approx 45 min at 110km/h (* @ 27C ambient)
  Warm Up City      89   Approx 20 - 30 min depends on traffic (* @ 27C ambient)
  1900kg Towing    89 -92  Hill & highway - various speeds (! @ up to 32C ambient)
  Heavy Towing     92 +  ?? Probably off-road, hill & traffic as well (**)
  High Temperature     110 +  ?? Over heating protection starts (**)
  Over Temperature     120 +  ?? Engine power is reduced (**)
  RED LINE      130  Stop & allow transmission to cool ***(owner's manual)

Due to lack of available (??) data this is a guide only

    * Tests were done with no load, UNeek bullbar & Warn winch  with round LED spotlights causing some air flow restrictions
    ! Test done with roof rack & cargo bay loaded, 2 tonne offroad camper/caravan & full fuel load (168Ltr) with the above accessories
  ** Data not confirmed due to lack of official information
*** Cool Down Procedure
  1. Stop vehicle - do not turn engine off
  2. Shift transmission into Neutral (?? see Note)
  3. Idle engine or faster until transmission cools down
Quote:
  1. "The 8HP transmission family is such an efficient transmission there is a need for an auxiliary heater to keep the transmission oil at the proper temperature, about 80C" (Chrysler MasterTech Update & Service Best Practice)  -?? Not sure how this auxiliary heater relates to hot  weather operation and possibly only refers to cold climates .
  2. "Additionally, lower viscosity transmission fluid is used resulting in improved transmission efficiency and fuel economy improvements    especially during cold weather or vehicle start-up. The 8HP45 & 8HP70 are 'fill for life' not requiring oil changes during  normal driving conditions."- www.wk2jeeps.com
Note:
  1. There is some difference between EVIC and Telltale procedures. The EVIC message (as per manual) reads  "Trans Hot Stop Safely Shift To Park Wait to Cool" but the "Transmission Temperature Warning Telltale" outlines  the cool down procedure. Take your pick.
  2. High temperatures operation will degrade the transmission oil fast, severely reducing it's life and ability to protect the transmission.
          Caution:
  • ATF+4 MUST always be used in vehicles that were originally filled with ATF+4.
  • ATF+4 is compatible with ATF+3 and can be used to top off vehicles that currently have ATF+2 or ATF+3.
  • DO NOT use ATF+2 or ATF+3 to top off vehicles that have ATF+4 fluid
  • 845RE & 8HP70 - Mopar  ZF 8&9 Speed ATF (p/n 68157995AA), Shell L12108 (Chrysler version of 8HP45 is called 845RE.)
   3.   Chrysler strongly recommends against the addition of any fluids to the transmission, other than those listed
         above.

Head Lights - Driving Lights

The right hand side head1ight 12 pin connector viewed front on: A1 top right hand pin and A12 bottom left hand pin.

Pin Wire Function
A1  WT/DB  Headlamp leveling sensor rear signal
A2  WT  Headlamp leveling sensor 5 volt supply
A3  BK/LG  Right headlamp return signal
A4  WT/LG  Can C Bus (+)
A5  WT/TN  Right low beam driver
A6  WT/VT  Lin bus lighting sig rt
A7  WT/DG  Headlamp leveling sensor front signal
A8  WT/BR  Headlamp leveling sensor return
A9  WT/GY  Right high beam driver
A10  WT/LB  Can C Bus (-)
A11  PK/YL  Fused ignition run control output
A12  WT/OR  Lin lighting

Note:  Check your vehicle VIN first for possible variations between models

How Bi-Xenon Headlights Work
Bumper and Headlight Removal
Headlight Wiring Diagram (2014) - Small because of diagram width so zoom required to view

The law on fog & driving lights: the majority of states appear to have adopted the latest version of Vehicle Standard (Australian Design Rule 13/00  with a few exceptions. Best to check with your State Transport Dept. if in doubt

LED Driving Lights & Light Bar

 A brief look at HID vs LED Driving lights:
  • HID (high intensity discharge) driving lights currently are the best long distance beam choice for 4x4 use with pencil beams extending out to around 1km 
  • HID lights require ballast units either internal or external to supply a high voltage to trigger an arc discharge between two electrodes in a sealed bulb.
  • HID lights are 20 % efficient while halogen lights are in the order of 5% efficiency; with both types most of the electrical power is dissipated as heat.
  • LEDs are very efficient drawing little power,  are extremely resistant to vibrations, have the advantage of exceptional long life and low heat dissipation.
  • LED driving lights are  ideal for use in rural areas and produce an intense bright white (determined by colour temperature) with spread beams illuminating out to 150m and up to about 550m depending on light output (Lumens).
  • LED Light Bars often combine both spread beam & pencil beams
Bulbs LEDs used for lighting are commonly labeled with their light output in lumens and colour temperature. While Lumen is an important factor, Lux
  • Lumens (lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a light  source.
  • Lux is defined as lumens (the total amount of light that a bulb is capable of generating) per square metre; eg if all the light from a 1000 lumen source is entirely focused on a 1m square area, the intensity at any point would be 1000 lux
  • Colour temperature is an important  characteristic of visible light and is stated as units of absolute temperature -  degrees Kelvin (K). Colour temperatures over 4,000K are considered cool colours (bluish white), while lower colour temperatures (2,700 - 3,000 K) are warm colours (yellowish white through red).
  • What are Cree LEDs? Simple answer is that they are a brand name for high quality power LEDs manufactured by Cree Inc a market-leading innovator of LED lighting. Because their LEDs are efficient and reliable they are sometimes used as a defacto measure to compare LEDs manufactured by other companies and are frequently used as power LEDs in many 4WD driving lights. This doesn't mean that other brands are inferior but does seem to assure a high level of  reliability and quality as far as the power LEDs modules go. Other electronic and hardware components used in 4WD driving light design and construction may vary considerably between driving light brands. Best to read all the reviews.
  • Width and area are more useful parameters for 4x4 driving lights; colour temperatures determines the quality of light emitted and height of the light pattern are important factors when choosing driving lights.  A very high Lux rating for greater distance may only produce a narrow beam which can leave blind spots on  road bends etc. while spread beams will light up road edges highlighting wild life, but are not suitable for long distances. The solution is to have a combination of both spread and pencil beam driving lights.
From Minor Modification Queensland Dept Transport and Main Roads

Headlights:

Retro-fitting High Intensity Gas-Discharge (HID) or Light Emitting Diode (LED) headlight assemblies to vehicles not
originally offered with the technology is generally not permissible as they do not comply with the ADRs because

  • no headlight self-levelling device is fitted
  • no self-cleaning function is fitted
  • the design of the headlamp reflector is compatible with the bulb (the light is not focused correctly).
Main (high) Beam Headlamps

The fitting of additional main beam headlamps is permitted without specific approval as they are mentioned under the
ADRs and the Transport Operations (Road Use Management - Vehicle Standards and Safety) Regulation 2010. These
additional lights may be fitted at any height above the ground but must only be fitted to the front of the vehicle.

Driving Lamps

The fitting of driving lamps (including LED light bars) is acceptable without specific approval, provided they meet the requirements provided in the Australian Design Rules. If you like a torturous read then look at Vehicle Standard (Australian Design Rule 13/00 

ADR13 has been revised several times since introduction and will undoubtedly be again in the future. Section 7.3.2.1 is the biggest recent change impacting 4X4 owners. The ADRs used to permit 'pairs of two or four it now simply states 'up to a maximum of four'. One LED light bar now  classed as one light. As for mounting light bars on the vehicle's roof, the ADRs don't rule on this so at this stage each state decides if it's illegal or not.  States that currently do not allow are NSW & WA . Always check before driving interstate rather than be fined.


Basically (as of 26/06/2016) :
  • Lamps should be installed symmetrically in pairs to the front of the vehicle.
  • One light bar centre mounted is allowed
  • A maximum of four lights (includes fog lamps in a bullbar if not originally fitted to the vehicle)
  • Must not protrude beyond the normal profile of the vehicle or bar
  • Must not block  the driver's field of view
  • Light produced must not cause the driver discomfort either directly or by reflection.
  • Must only come on when the main-beam (high beam) headlamps are used, and must automatically turn off when the  main-beam headlamps are turned off.
Note:

Pay particular attention to  'up to a maximum of four' which  refers to additional lights and includes fog lamps in a bullbar if the vehicle wasn't originally fitted with them. Also light bars mounted above bullbars will certainly earn you a defect notice if they obstruct the drivers view or protrude beyond the vehicles profile

Daytime Running Lamps and Fog Lamps

The fitting of daytime running lamps and/or fog lamps is acceptable without specific approval, provided they meet the requirements provided in the ADRs


Headlight Adjustment

Now what to do when lifting a vehicle!!..Obviously lifting is going to lengthen the low beam illuminated distance to the point where they will dazzle on coming traffic and cause the driver to flash their headlight in annoyance. Conversely too low is dangerous. If this is the case then low beam realignment is essential and a legal requirement.


Aiming using a 10 metre wall: This method is mainly used today for vehicle with headlights higher than 140cm but in the absence of expensive professional optical beam-setter equipment,  it can be used to achieve excellent results as a DIY headlight alignment procedure: See WK2 Headlight Alignment Guide

Adjustment Screw Location

 Steel Suspension Lift Kits

Read this first About MC & MA Classification

2016 Suspension changes (effects certain lifts)

Minor Modification Queensland Dept Transport and Main Roads - Vehicle Standards Instruction G19.1:

The raising of a vehicle's suspension (coil spring suspension) is permitted without specific approval, provided:
  • at least two thirds of the original suspension travel in either direction is maintained
  • coil springs remain in locating seats on full suspension droop
  •  the normal relationship between the front and rear suspension heights is not unduly affected
  • replacement springs have the same or greater load capacity as the original springs
  • a vehicle fitted with Electronic Stability Control (commonly known as ESC) is not modified if the operation of the ESC is affected, unless the ESC system is adjusted accordingly.
Steel Suspension:

Rocky Road recommend suspension lifts be capped at 2.5"as not to exceed factory tolerances. They have tested a variety of tyre sizes and found that 33" OD tyres would fit with minor trimming of the inner guard felt liners. A +30mm offset rim is required (OE offset + 56.4mm - 25.4mm) instead of their suggested 1"(25.4mm) spacers which are illegal on Australian roads.

QuadraLift Suspensions:

For those who purchased an airbag suspension for your Jeep, unfortunately you will never be able to install a permanent lift system to your Jeep. They can lift and lower by pushing the buttons, but will never be able to install larger tyres (sic) since the suspension will always return to its original "stock height"

New Vehicle Measurements
Ground Clearance (4x4 only) Laredo (mm) Limited (mm)  (Inch) 
    Standard Steel Suspension      218       218    8.6
    Quadra-Lift, normal ride height      205       205    8.1 
    Quadra-Lift, Off-road I      238        238     9.4
    Quadra-Lift, Off-road II      271       271   10.7

4x4 Standard Steel Suspension
 Ground Clearance  Inch  mm 
    Front Axle   9.3   236
    Rear Axle   10.0   253
    Fuel Tank   9.6   243

Some Lift Kits:

 

Things to Check before lifting:

Read this first: About MC & MA Classification then if certain:

First measure front and back before getting your lift installed so you can verify the lifted height..Measure from the lower edge of the wheel arch trim to the exact center of the CB cap...Check again before leaving the installer. The following image & table shows the approximate measurements taken from a new Laredo:

The new Laredo measurements were from 3 different new showroom stock standard Laredos (only one included) both diesel & petrol all measuring approximate the same and near enough not to distort the data. This table, while measured with a tape, is as accurate as possible using this method and is indicative should be before lifting.

Measurements front & rear should be done from the inner trim on the wheel arch to the centre of the wheel hub directly in line with the centre of the wheel.



WK2 Wheel Arch To Hub Centre Table
What ARB say in their brochure:

"A 50mm lift was achieved and 2 progressive rate spring designs were created to cater for medium loads and constants loads of 200kgs. As the Jeep WK2 is available with an optional tow pack, 2 different designs needed to be created. The tow pack option introduces a Nivomat (self levelling) rear shock absorber which has a different top pin mount and different extended and compressed lengths. With 2 different shock designs and 2 springs to cater for loading options, this resulted in 4 different shock options for the rear. Please note when replacing Nivomat shocks, you must fit the appropriate OME spring. To identify whether a vehicle has the standard fitment rear shock or Nivomat shock, the outer body diameter will need to be measured."

Standard fitment: 51mm
Nivomat: 63mm

How to remove Nivomat SLS (video not specific to Jeep WK2 GC)
Checking Nivomat SLS (video  Jeep WK2 GC)

Headlight Alignment After Lifting

After fitting a lift kit there is every possibility that on Low Beam your headlights will blind on coming traffic. For safety reasons it is important that your headlights meets ADR alignment standards..The solution is to readjust your headlights

 Quadra-Lift Air Suspension

LLAMS Kit

The LLAMS electronic air suspension height controller kit provides the ability to raise the vehicle by approx 32mm/1.25" or 55mm/2.2" whilst at normal ride height, therefore without speed limitations, to allow improved ground & bump stop clearance when travelling off road on high crown gravel roads or other off road conditions where extra clearance is required.

Approx Height Changes:

Low: -22mm/-32mm depending on vehicle setting at calibration.

Off: No change
Medium: +32mm
High: +55mm
Using Llams high with OR1 will add approx 30mm to OR1
 

WK2 LLAMS Height Controller

Davis Performance
How does QuadraLift Work
QuadraLift Front Springs

 Towing & Loading

Reduced Towing Maximum:
The WK2 CRD & 5.7L V8 can tow up to a maximum of 3500kg (see Note)...If the Nivomat self levelling shock absorbers  (SLS) are replaced with standard shocks then the 3500kg towing maximum is downgraded (Note 3). Since most spring lift kits replace the OE Nivomat SLS with a standard type, check with the lift kit supplier first and ask if there is any detrimental effect on towing specifications.

Regardless of what lift kit you chose, if replacing the Nivomat SLS with standard shocks,  you must replace the Nivomat  springs as well otherwise they will sag noticeably under increased loads

Why different spring ratings for Nivomat system?...Because the Nivomat SLS share the load with coil springs and adjust for any load variation, the springs don't have to support all the load so are softer to provide a more comfortable ride at low loadings.

Is you wish to retain 3500 kg towing, keep the Nivomat  SLS and fit Nivomat compatible rear springs rather than constant load springs used with standard shock absorbers. If towing is not your thing then this probably isn't an issue apart from ride comfort.
Note:
1. Jeep Australia issued a National Dealer Bulletin 72/2011 stating that a Weight Distribution Hitch is suitable for use with all available WK2 Grand Cherokee suspension systems and it is mandatory when towing an ATM above 2268kg.
2. Vehicle and caravan insurers' advice relating to a claim arising from an accident, is that you should comply with manufacturers recommendations at all times.
Nivomat Self levelling system (video not specific to Jeep WK2 GC)
Level Your Jeep WK2 Grand Cherokee

 

To understand about your vehicle's load limits and actual towing capacity then it is essential to know  terms used:
  • Kerb Mass :  the unladen mass of the vehicle unoccupied but including full fuel load & standard equipment
  • Tare Mass (vehicle): the unladen mass of the vehicle unoccupied with standard equipment but excluding fuel (10 litres allowed)
  • Tare Mass (Trailer):  the unladen mass of the vehicle
  • Gross Vehicle Mass (GVM): the maximum allowed  mass of the vehicle including its load.
  • Gross Combination Mass (GCM): the maximum allowed mass of a loaded vehicle (GVM) plus its loaded caravan/trailer (GTM)
  • Gross Trailer Mass (GTM): the maximum allowed mass supported by the axle/s or wheels of a loaded caravan/trailer 
  • Aggregate Trailer Mass (ATM):  the total legal loaded mass of a caravan/trailer including the tow ball download weight (TBM)
  • Tow Ball Mass (TBM) / Download Weight: the mass transferred by a caravan/trailer onto the rear of a tow vehicle
  • Payload:  any mass added to the Tare Mass of a vehicle or caravan/trailer.
  • Maximum Towing Mass (MTM) : the maximum caravan/trailer weight (ATM) that a vehicle can legally tow (braked/non-braked)
  • Maximum Towing Capacity (BTC): same as  braked MTM
In the following text: caravans, camper trailers and all other towables are referred as trailers and Tare Mass as Tare so:

GVM = Tare Mass + Maximum Payload  (Vehicle) - includes any TBM when hitched to a trailer
ATM = Tare Mass + Maximum Payload  (Trailer)
GTM = ATM - TBM
GCM = GVM + GTM

The question now is: how much can you really carry in your vehicle when towing at the maximum tow capacity specified by the manufacturer?

The true capability of a vehicle in practice is dictated by the GCM (often called GCVM), the vehicle's GVM plus trailer's GTM...Note that GTM is used  instead of ATM ...GTM is different to ATM in that it does not include that part of the trailer's mass exerted on the vehicle's tow ball (TBM) when hitched up....TBM has be included in the tow vehicle's Payload i.e. more ball load weight then less the vehicle can carry. To determine what load you can actually carry when towing, simply subtract the vehicle Kerb Weight (or Tare) plus its rated tow capacity from the GCM. The result is the available payload  i.e. the total of cargo plus accessories (bullbar, winch, roof racks, tow bar, etc), driver and passenger weights  - you may be surprised how little it is..When not towing the vehicle's payload capacity is at maximum, so what can be legally towed, when the vehicle is loaded to it's GVM??...This can be substantially lower than the vehicle's rated tow capacity...surprise surprise!!

Example: 2015 Ford Everest:
Towing and Vehicle Mass   Ambient       Trend    Titanium
  ATM (Towing Capacity kg)   3000     3000    3000  
  GCM  (kg)   5800    5800    5800 
  GVM (kg)    3100    3100    3100 
  Kerb Weight (kg)    2370   2407    2495
  Payload (kg)           730         693        605
                   
      Using:        GTM = GCM-GVM
                                   = 5800 - 3100 = 2700kg
                         ATM = 2700 +  300 = 3000kg (TBM =10% of ATM = 300kg )

      Now since TBM is part of the GVM when towing:
                         Available Payload = 730 - 300 = 430kg (Ambiente Model)
      Loading up:
     Bullbar & Winch 100kg
     Available Payload = 430 - 100 = 330kg  for passengers, cargo & accessories.
     Add roof rack, and aux fuel tank (full) say total 125kg  (no allowance made for the tow hitch ??kg)
     Available Payload  = 205kg for passengers and effects
     Assume passengers (2) = 150kg
     Available Payload = 55kg

Jeep Australia doesn't normally provide a GCM for Australian models and it's not required to...GCM is a requirement for commercial vehicles that carry a load & tow.   

Example:  2014 -2016  4x4 3L Diesel Laredo (no GCM specified)
 Towing and Vehicle Mass    Laredo 4x4 3L Diesel   
 ATM (Towing Capacity kg)               3500  
 GVM (kg)                2949 
  Tare (kg)               2267

      Using   :     GCM    = GVM  + ATM - TBM 
                                       = 2949kg + 3500kg  = 6449kg - 350kg  = 6099kg

                         GTM    = ATM - TBM
                                       = 3500 - 350 = 3150kg

                         Payload = GVM - Tare
                                        = 2949 - 2267 = 682kg 

     Now since TBM is part of the GVM when towing:

                        Available Payload = 682- 350  = 332kg
     Loading up:
     Bullbar & Winch 100kg
     Available Payload = 332- 100  = 232kg  for passengers, cargo, accessories & tow hitch
     Add roof rack, rock rails and aux fuel tank (full) say total 155kg  (no allowance made for the tow hitch ??kg)
     Available Payload  = 77kg for passengers and effects 

Example:  2017 4x4 3L Diesel Trailhawk (GCM now specified)
 Towing and Vehicle Mass    Laredo 4x4 3L Diesel   
 ATM (Towing Capacity kg)               3500  
  GCM (kg)               6099 
 GVM (kg)                2949 
  Tare (kg)               2340

GCM = GVM +ATM - TBM
            = 2949kg + 3500kg - 350kg = 6099kg

Payload = GVM - Tare
               = 2949 - 2340 = 609kg

Now since TBM is part of the GVM when towing:
Available Payload = 609 - 350 = 259kg

Loading up:

Bullbar & Winch = 100kg
Available Payload = 259 - 100 = 159 kg for passengers, cargo, accessories
Add roof rack, rock rails and aux fuel tank (full) say = 155kg
Available Payload = 4kg for passengers and luggage

Note:

  • Trailhawk tare is heavier because of bash plates, Quadra-Drive & Quadra-Lift
  • Kerb Weight is the same as Tare Mass, but with a full tank of fuel and without any accessories fitted
Quote:

"The rated tow figure of the Ranger is 3500kg, while the GCM is 6000kg – much the same as many of the dual-cabs. This means the maximum car weight has now dropped to 2500kg – a payload decrease of 700kg. That means the maximum weight you can carry in a Ford towing a 3500kg caravan is just 300kg. That’s not much more than two healthy adults, a pet dog and a full tank of fuel" (by Ron Moon 4x4 Australia Sep 15, 2016)/span>

Conclusion:
 
It's a pity the salesperson did not tell you the truth when asked about towing & payload. In other words GCM does not always equal GVM + MTM braked (BTC) so do your sums and stay legal.
 
 

WK2 Jeep Grand Cherokee Weight & Towing Specifications (kg)



Weight Distribution Hitch (WDH)

The official Chrysler figures for the Grand Cherokee diesel are 350kg on the ball max and 3500kg trailer max and that Chrysler requires a Weight Distribution Hitch for towing loads which exceed 2268-2270kg. The 2kg difference depends on which set of specifications.

Don't get caught in the "big van" towing trap

Generally speaking the  the TBM should be within 10% of the total trailer weight. Assuming that you wish to tow at the vehicle's towing maximum then the TBM would be about 350kg  which has to be accounted for as part of your GVM (all accessories to be included), this could mean your vehicle and caravan combination has crossed into illegal weight territory without a driver or passengers or any payload you need to carry aka the 3500kg towing trap.

Do you homework and don't ignored the limits i.e. GVM,GCM,GTM & ATM  when buying your caravan/camper.  In practice, what you think you can tow may not be what you can without exceeding manufacture's specifications. The choice is between a fully loaded vehicle with all the accessories or the heaviest caravan/trailer. So if you tow a big caravan, then don't expect to carry a full load (all occupants & accessories) in your vehicle. Very few vehicles can actually tow at their maximum rated capacity when loaded at their GVM. Of course you can juggle between payload and caravan/trailer weights to find a combination that suits your purpose.
 Exceeding a vehicle's GVM  will most certainly void manufacturer's warranty and your insurance as well as illegal implications. To reduce vehicle load to stay within the vehicle's GVM, make use of your caravan/trailer's GTM (do not exceed) and distribute load evenly to avoid trailer instability.

WK2 Grand Cherokee Specifications (Australia)
Towing Limit Question??

Quote: 

"If you are on a  weighbridge with your tow vehicle hitched up to the caravan/trailer and are all loaded up this will give you the Gross Combined Mass (GCM). If you have the loaded caravan/trailer unhitched (on it's jockey wheel) with its wheels on the weighbridge this will be the Aggregate Trailer Mass (ATM). With the van/trailer hitched to the tow vehicle with only the van/trailer's wheels on the weighbridge this will give you the Gross Trailer Mass (GTM). The difference between the ATM and GTM will give you the Tow Ball Mass (TBM)" - (from (lets-getaway.com)

Everything you need to know about towing heavy trailers

Manual Park Release

To move a disabled vehicle e.g. where the transmission will not shift out of PARK (such as engine won't start)

Now that the Park selection software update has been installed, you can't leave the engine running , select neutral, hop out and push the vehicle..Now when you open the door the Park is automatically selected. Also if the engine won't start how do you move the vehicle?? Well this is how in both cases:
A Manual Park Release is available even if a little tricky and not well known to many owners but once you know quite easy but take care to prevent roll-away.

Warning

Activating the Manual Park Release will allow your vehicle to roll away if it is not firmly secured by applying the "foot operated" parking brake or tow rope/recovery strap it to a tree/post or another vehicle to prevent the vehicle from rolling unintentionally. Activating the Manual Park Release on an unsecured vehicle could lead to serious in­jury or death for those in or around the vehicle.

Basically what you do to use the Manual Park Release:

1. Firmly apply the parking brake.
2. Open the center console and locate the Manual Park Release cover


 

3. Remove it by snapping the cover away from the console hinges
4. Using a screwdriver or similar tool, push the metal latch in towards the tether strap.
5. While the metal latch is the open position, simultaneously pull upwards on the tether strap until it clicks and releases out of the park position.


To Disengage the Manual Park Release Lever

1. To disengage the Manual Park Release ap­ply tension upward while pushing the release latch towards the tether to unlock the lever
2. Once the tension has been released and the lever has been unlocked be sure it is stored and locked into   position
3. Replace the cover


 Suspension Load Assist Kits

The pros and cons about adding airbag suspension assist kits:

Adding airbag (aka air spring) suspension load assist kits will not change the GVM, GCM & maximum rear axle load rating of your vehicle (see above discussion about Towing & Loading). Vehicle manufacturers will specify a maximum weight allowable for each axle. So even if your total weight is under the specified GVM, you may still be over an individual axle’s maximum load rating. You should never exceed your vehicle’s Max Weight Ratings under any circumstance. Airbags simply increase your ability to level your vehicle with heavy loads.

The problems I've had:

Airbags look like a good idea and when inflated function well..No worries if the airbags stay inflated and often do...This didn't happen on my last trip up the OTT Cape York last November (2106)..One airbag went down with a leak at the airline coupling (after all the articulation on creek crossings - probably to Bathurst Bay) and wouldn't hold air so I had to let both down to keep the back from leaning and slamming down on one side ..Problem without the airbags inflated on the OTT, the rear suspension continually bottomed out and the tyres eventually ripped into the inner guard liner..The combination of medium load springs and OME nitro shock absorbers with the  larger diameter 265/65R18s tyres turned out to be a mistake ...Why??...These medium load springs need the OE Nivomat shocks to share the load and provide a bump stop function which the standard shocks don't do. Relying on airbags to do this isn't wise..Also the airbags I had installed were for standard height suspension so not that effective with my 50mm lift kit.. I have since procured new airbags 25mm longer than standard to compensate for the raised vehicle height and reinstalled the Nivomat shocks.. Custom made 30mm poly spacers placed  under the standard airbags would probably work with a 50mm lift also.

Now this presents a decision problem in that you need to work out what your needs really are: medium load springs or 300kg springs..If you tow and load up then 300kg springs are probably what you need but may ride a rough when unloaded..Medium load springs are probably too soft for towing a caravan + cargo (see above discussion on Reduced Towing Maximum) unless you keep the Nivomat shocks to share some of the load..If the Nivomat shock absorbers are replaced (ie with suspension lift kits), Polyair or Airbagman (Firestone Coil-Rite) airbags can level the vehicle providing they are suitable size for your suspension height but don't rely on them as I found out..Reliability off road can be an issue as per my experience...Be good if airbags had pressure monitors to detect failure..Maybe an On Board Air Control Kit option is worth looking at but probably no help if an airbag develops a leak - I'll let you be the judge on the pros & cons.


Rock Rails

Mopar Rock Rail/Sliders
Uneek Rock Sliders
Rocky_Road Rock Sliders

Note: OE mud flaps will not fit with Mopar rock rails on so will require some trimming: See Trimming Template

  



If you do decide to fit UNeek sliders remember they are 20mm too short so there will be a 20mm gap either at the front or the rear depending on how they are installed. If the sliders are installed towards the front (instructions say to the rear) in order to neatly fit front mud flaps then there will be a 20mm gap at the rear as well the upper body panel.



One solution is to cover this upper panel gap with rubber strip shaped to fit and glued to the upper slider surface and to fabricate a 20mm rear extensions from either steel or aluminium. See UNeek Rock Slider Installation Issues. Alternatively if front mud flaps are not needed and the sliders are installed as per instructions then a similar extension can be fabricated for the 20mm front gap if considered unsightly..Pity the Mopar rock rail/sliders are no longer available and the UNeek Sliders are made in this fashion.


Note: The following is for a forward installation only  
   
Rear Slider End 20mm Extension


Trimmed To Fit UNeek Slider



Sill Bracket To Secure Mud Flap Tab

See Trimming Template


Roof Racks

Caution:
The 68kg (150lb) is the Maximum OE load specification and MUST NOT BE EXCEEDED - Read Safety Notes,  
See
: Roof Flex Video
Note:
Rhino state when used off road you must reduce the maximum roof load by 1/3 - Rhino Rack Heavy Duty Crossbar Maximum Roof Load. Rocky Road, GOBI & Front Runner do increase roof load limit by replacing the OE roof rails with stronger mounting systems - refer to their sites for specifications. UNeek specifications are: Caged rack is rated to 150kg dynamic and 300kg static (evenly distributed & Slim line rack is rated to 125kg dynamic and 250kg static (evenly distributed) by use of steel mounting brackets which divert the load off the top buttons and relocate it to the welded seam on the roof join for far better load capacity.  
Mopar Installation
Rocky Road Crossbar Kit
GOBI Stealth Roof Rack
Rhino Roof Rack
UNeek Roof Rack


WARNING: When fitting a new  roof rack system where OE roof rails have to be removed and replaced,  before fitting the new roof rails be sure the end nutserts (rivnuts) normally hidden under the plastic end covers,  are thoroughly cleaned. Unless this is done then when fixing any new rail system, the screws may bind in the threads causing the nutserts to spin making it almost impossible to extract the screws. If binding does occur then removing the interior lining at the rear to access and clamp the nutsert may be necessary. Also if dirt build up is present lower in the rivnuts then screws may be too long and will require shortening to firmly secure the new rails. This is especially concerning the rear nutserts where dirt buildup is common but not seen.. Another thing to watch for is rubbing through the painted surface cause but movement of the OE rails under load. This will need recoating before new rails are fitted to prevent future rusting.

Auxillary Batteries

There is only one battery that is best suited for safe mounting inside the WK2 for use as an auxillary battery to run fridges and other accessories - a deep cycle "Absorbed Glass Mat" (AGM) battery. AGM batteries are available as either Starting or Deep Cycle. The WK2 main battery is an AGM starting type.

Why??

Batteries come as either Starting, or Deep Cycle. Starting (cranking) batteries are designed to supply large current for a short period.. Deep cycle batteries are more suited to long slow power draw and slow recharge.

A good wet cell cranking battery will have a limited life when being used as an auxiliary battery A marine battery is a semi deep cycle battery will last longer than a standard wet cell battery.

AGM totally sealed, transport class batteries don't require venting to the outside like wet batteries, so are ideally suited for mounting inside a 4WD. They are spill proof and therefore can be mounted at any angle. These batteries will accept a much higher charge current so will charge faster without damage and can be discharged much deeper than conventional deep cycles without major damage. They also have a very slow self discharge rate resulting in a longer shelf life.  When fully charged, they can be stored for extended periods and conveniently recharged successfully.

4x4 Dual Batteries
Dual Battery Systems Review
Red, Yellow & Blue Optima Batteries





About Charging
About Testing

How To Charge AGM batteries
REDARC BCDC In-vehicle Chargers
Portable AGM Dual Battery System
Dual Battery System Isolators

Battery Testing Methods
Testing Lead Acid Batteries
Battery Testing Guide
Dual Battery System Testing
Troubleshooting Battery Isolators
Battery Analyser & Testing Equipment


Variable Voltage Alternators

In Australia, as of 2013, new vehicleshave to comply with the Euro 5 exhaust emissions standards and from 2017, the tougher Euro 6 standards. The ECU in these vehicles controls the alternator by monitoring its electrical loading. The ECU adjust the output voltage determined by load changes and in some cases can completely turn it off. These alternators are referred to as Variable Voltage Alternators. (In brief from Redarc - New Vehicle Technology Can Affect Dual Battery System's Charging Performance - Technically Speaking) - See:

New Vehicle Technology Can Affect Dual Battery System's Charging Performance - See:


In order to avoid costly ECU replacement and get your alternator working, you can simply bypass the internal Alternator Voltage Regulator Control Module using an External Voltage Regulator Conversion Kit -See:
 
Note:
Brief descriptions to the above links have been either summarised or extracted from those sites. Please refer to them for detailed information.
Wheels & Tyres

In order to understand wheels and tyre technology it is essential to first understand the terminology of wheel rims & the curious mix of both imperial (inches) and metric measurement used. Industry standard is to specify offset in millimeters whereas other measurements are normally in inches

Offset & Backspacing

Offset (ET) specifies where the hub mounting surface sits with respect to the centreline of the rim and  is based on the overall width of the rim, not the stated width. Most rims are 1” (25.4mm) or wider than stated i.e. a 7.5” rim will actually measure 8.5”. Changing the offset moves the rim in or out, changes the amount of mechanical leverage on axle and suspension components, wheel track and of course backspacing.

Rim offset can be one of three settings:

  • Zero offset:The hub mounting surface is even with the centreline of the rim.
  • Positive offset: The hub mounting surface is towards the front of the rim forward of the rim centreline.
  • Negative offset: The hub mounting surface is towards the back of the rim behind the rim centreline . "Deep dish" wheels are typically negative offset. Too much negative offset can place stress on suspension and axle components resulting in premature failure.

Backspacing is the distance from the back edge of the rim (inboard flange) to the hub mounting surface and determines the amount of clearance between the wheel and suspension components. Backspacing is necessary to calculate where the rim's inner flange will sit with respect to suspension components. The hub mounting surface is always a fixed distance from these components so if the rim width is changed it will immediately affect these clearances as will changing the offset.

Calculations using rim width and backspacing for sufficient clearance will also determine offset relative to the centreline of the rim. Clearances will obviously be different from vehicle to vehicle. So when buying a rim, you'd specify rim PCD, rim diameter, width and ET (offset) e.g. 5x127mm 18x8" ET 56.4 mm. Note that ET is specified rather than backspacing.






Fitting 265/65R18LT Tyres

Read this first About MC & MA Classification

From 2015 to present WK2 Grand Cherokees are currently classified as MA passenger vehicle not off road use MC so:

MA-rated vehicles are more restricted in what tyres can legally be fitted, because of speed ratings & specifically to that which the manufacturer has specified on the compliance plate. You can’t fit a tyre with a lower speed rating to an MA rated vehicle..Since there isn't any LT-construction, off-road tyres with high speed ratings currently available, then by the rules you’d be fitting an illegal tyre.



An LT265/65R18 tyre mounted on an OE alloy rim will fit in the cargo spare wheel well if turned the opposite way up allowing the lid to close level with the cargo bay floor. One modification is required though (shown in the following photos): the OE securing bolt has to be lengthened because of the way the larger tyre has to be seated to fit...An M14 x 2mm pitch x 200mm bolt with the hex head cut off is  welded it into a close fitting steel tube and opposite end tapped and threaded with the original securing bolt screwed in and thread locked.



Note: 2x plastic storage bins have to be discarded


2014 Grand Cherokee 3.0Ltr CRD Laredo OE Wheels

 
  Tyre Size   Rim Type Rim  Width Offset Backspacing CB PCD Nut Size
 265/60R18   8Jx18 ET56   18" 8" 56.4mm 6.7" 71.6mm  5x127mm   M14x1.5 

Backspacing to Offset Conversion

(Backspacing - (Rim Width/2 + Flange Width )) x 25.4 = offset

Offset to Backspacing Conversion:

  • Positive offset rims: Rim Width/2 + Flange Width + offset x 0.03937 = backspacing
  • Negative offset rims: Rim Width/2 + Flange Width + offset x 0.03937= backspacing
Where:
  • rim width is measured between the inner edge of the rim flanges
  • backspacing, rim width & rim flange width are in inches
  • offset is normally quoted in mm as industry standard
  • rim flange width is usually about 0.5" but check rim information

Offset, Rim Width, Backspacing Cross Reference 
 Offset (mm) BS 4.25" BS 4.5" BS 4.75" BS 5" BS 5.25" BS 5.5" BS 5.75" BS 6" BS 6.7"
RW  7.5" 0 6 13 19 25 32 38 44 63
RW  8" -6 0 6 13 19 25 32 38 56
RW  8.5" -13 -6 0 6 13 19 25 32 50
RW  9" -19 -13 -6 0 6 13 19 25 44
RW  9.5" -25 -19 -13 -6 0 6 13 19 37
RW  10" -32 -25 -19 -13 -6 0 6 13 31

Offset is calculated using the above Backspacing to Offset formula and truncated to nearest mm.

Conversion Metric to Imperial to Metric

29" Tyre Diameter 30" Tyre Diameter 31" Tyre Diameter
245/60R18 = 29.6x9.7R18
255/55R18 = 29x10R18
265/55R18 = 29.5X10.4R18
275/55R18 = 29.9x10.8R18
285/50R18 = 29.2x11.2R18
245/65R18 = 30.5x9.7R18
255/60R18 = 30x10R18
265/60R18 = 30.5x10.4R18
285/55R18 = 30.3x11.2R18
265/65R18 = 31.6x10.4R18
275/60R18 = 31x10.8R18
285/60R18 = 31.5x11.2R18
 32" Tyre Diameter   33" Tyre Diameter  34" Tyre Diameter
265/70R18 = 32.6x10.4R18
275/65R18 = 32.1x10.8R18
285/65R18 = 32.6x11.2R18
275/70R18 = 33.2x10.8R18
285/70R18 = 33.7x11.2R18

285/75R18 = 34.8x11.2R18



Possible Adverse Effects  

What wheel is safe or unsafe to repair??

National Code of Practice for Light Vehicle Construction and Modification  Tyres, Rims, Suspension & Steering

About Fitting Light Truck Tyres
Note:

Regardless of its type and size, every tyre's load capacity, durability, traction and handling depends on using the right inflation pressure for differing operating conditions. Since both too little and too much inflation pressure sacrifices some of the tyre's performance, maintaining the "right" inflation pressure is important. Every tyre has a maximum inflation pressure rating stamped on the sidewall somewhere. This is the maximum permissible pressure a tyre can be safely inflated to. It is not the pressure it should be inflate to for normal operation..

Caution:
  • Size-for-size, Light Truck (LT) tyres require higher air pressures than Passenger (P-Metric) tyres. Failure to adjust air pressures as recommended will result in premature tyre failure due to excessive heat build-up..
  • When choosing a tyre it's construction must be suitable to carry the vehicle’s weight, dynamics and intended use. A wrong choice can and often lead to an accident possibly causing serious injury as well as insurance claims rejected. .
  • The differences in load capacity and inflation pressures prohibits mixing the LT-metric tyres with P-metric tyres or visa versa. For maximum safety and performance, every tyre on a vehicle should be identical.

Ply Rating:

LT tyres can vary in construction ranging from 4 tread plies up to 8 or 10 ply. The more plies the better protection against stone damage but ride comfort will suffer. The number sidewall plies is a good measure of sidewall staking resistance.
This is a good point to note that ply rating is no longer the number of actual physical plies in the tyre. For example a 10 ply equivalent rated tyre may only have 6 physical plies; 3 polyester, 2 steel and 1 Nylon and 3 polyester ply sidewalls.

 

Laredo Original Equipment Placard:

Load Index 110 (1,060 kg) Speed Index H (210 km/h)

Tyre Sizing:

International Standards Organization (ISO) Metric system combines the metric system with a service description. The service description specifies the load index and speed rating symbol. plus an optional letter for intended use or vehicle class for the tyre:

The ISO-Metric tyre sizing system: 

 265/65R18 122R

  • 265 = tread width (mm)
  • 65   = sidewall aspect ratio (%)
  • R    = radial ply
  • 18   = rim diameter (inch)
  • 122 = load rating  (kg)
  • R    = speed rating (km/h

Optional use or class prefix:

  • P: Passenger Car
  • LT: Light Truck
  • ST: Special Trailer
  • T: Temporary (restricted usage for "space-saver" spare wheels)
Passenger Tyre:

P245/65R18 110H (P-Metric)

Light Truck Tyre:

4WD owners will be confronted with 3 different LT tyre size descriptions

1) LT265/65R18 122R (LT-Metric)

2) 9.50R16LT (Light Truck Numeric)

  • 9.50 = width (inch)
  • R     = radial ply
  • 16    = rim diameter (inch)
  • LT = light truck construction

3) 32x11.50R15LT (Light Truck High Flotation)

  • 32      = diameter of tyre on rim (inch)
  • 11.50 = width (inch)
  • R       = radial ply
  • 15      = rim diameter (inch)
  • LT     = light truck construction
Note:

Flotation-sized tyres have wider overall width, as the size dimensions increase, than LT-Metric and LT-Numeric sizes as well as  requiring wider rim widths..


LT vs. P-Metric
  • P-metric tyres are typically lighter, with less rolling resistance and less aggressive tread designs than most LT tyres. Because of better ride qualities, fuel efficiency and less road noise, P-metric tyres are being supplied as original equipment on SUVs and many light trucks.
  •  LT tyre's heavier construction in sidewall, shoulder and tread areas are better for off-road rough-terrain use while P-Metric tyres are more suited to on-road use ratter than off-road. The confusing thing here is that many All Terrain (AT) tyres are actually P-Metric so are rated as % on-road and % off-road e.g  medium duty 70% Road & Sand, 30% Dirt & Mud or heavy duty 50% Road & Sand, 50% Dirt & Mud
  • LT tyres do require higher pressures than P-metric tyres for a given Load Index. Operation at maximum load carrying capacity (Load Index) with lower than recommended air pressure will cause excessive overheating due to the heavier construction preventing heat dissipation.

Load Speed 
Index Max Load
110 1,060 kg
111 1,090 kg
112 1,120 kg
113 1,150 kg
114 1,180 kg
115 1,215 kg
116 1,250 kg
117 1,285 kg
118  1,320 kg
119 1,360 kg
120 1,400 kg 
Index Max Speed
N 140 km/h
P 150 km/h
Q 160 km/h
R 170 km/h
S 180 km/h
T 190 km/h
U 200 km/h
H 210 km/h
V 240 km/h
Z Above V
W 270 km/h
Y 300 km/h

MY2014 WK2 Laredo Placard OE Tyres

Warning:

Australian Design Rules (& State laws) allows for fitment of lower speed rated tyres on 4WD vehicles other than that specified on the vehicle's original equipment placard  but must be no less than 'N" rated (140km/h)

US Tyre Ratings

UTQG ratings (Uniform Tyre Quality Grading) must be marked on the tyre's sidewall in the US tyres sold in Australia may not have a UTQG rating so it can be difficult to compare the quality of these tyres in terms of tread-wear, traction, & temperature.


Example:

150AB

  • 150 = treadwear
  • A traction
  • B temperature

Where:

  • Tread-wear rating is used to compare tyres. A tyre rated 150 should last 1/2 as long as one  rated 300 but  conditions of their use due to differences in road characteristics and climate will vary tyre wear rate.
  • Traction rating  AA, A, B, and C (highest to lowest) indicates a tyre's ability to stop in a straight line on wet surfaces but does apply to hydroplaning or to cornering traction.
  • Temperature rating  A,  B and C  (highest to lowest)  indicates a tyre's ability to sustain high temperatures which cause tyres to wear quickly or in extreme conditions, sudden failure.
Date of Manufacture

All tyres are stamped with the date of manufacture either three digits for pre-2000 or  four digits for after 2000

The Correct Air Pressure??

Under-inflation is the biggest destroyer of LT tyres while over-inflation increases risk of punctures, wear and decreased ride comfort as well a vehicle instability and increases stress on suspension components; so  how to determine what is the correct air pressure??

The way I do it:
  • Note the tyre max pressure (marked on the sidewall) and do not exceed it
  • Note the vehicle's recommended placard (cold) tyre pressures and inflate to this pressure when tyres are cold
  • Use the 4 PSI Rule to find the ideal tyre pressure for differing load and towing conditions
  • Record these pressures for future reference
The 4 PSI Rule:
  • Inflate tyres to the recommended cold tyre pressures with the vehicle in the shade (all wheels) and not driven for at least 1 hour.
  • Drive the vehicle at highway speed for at least 1 hour or 50km.
  • Check  tyre pressures.
  • If pressures are correct then tyre pressure should rise between 2 and 6 psi (Jeep manual) with 4 psi optimum for P-metric. For LT tyres, due to higher maximum pressures, the rule is modified with the optimum towards the higher end (5-6 psi). LT tyres do require higher pressures to stiffen sidewalls to reduce heat buildup under load (load Index). 
  • If pressure rise is less, then cold inflation pressures have to be increased
  • If too high, then cold inflation pressures needs to be reduced.
Establishing Initial Cold Inflation Tyre Pressures.

When fitting tyres other than the OE standard tyres then the vehicle's placard recommended pressures will probably be
unsuitable. A good method of establishing initial cold inflation pressures is:
  • Take the max weight the tyre can support (on sidewall) and multiply it by 4.This gives the maximum total weight all four tyres can support.
  • Next take the weight of your Jeep plus 20% (safety margin) and divide it into the maximum total weight.
  • Now divide this number into the maximum psi stated on the sidewall and you'll have your cold inflation pressure.
Example: BFG LT265/65R18

Kerb Weight (Tare Mass) = 2191kg (Diesel Laredo)
Max Sidewall Rating = 1500kg at 80 psi
Max Total Weight = 1500 x 4 = 6000 kg
Vehicle 20% Safety Margin = 2191 x 1.2 = 2629kg
Constant = 6000/2629 = 2.28
Cold Inflation Pressure = 80/2.28 = 35psi (2.4 bar)

This method will give a good starting point for the “4 psi Rule” to refine the correct (unloaded) operating pressures.
If loaded to GVM then substitute vehicle's GVM instead of Kerb Weight.

Tyre pressures should be checked when the vehicle has not been driven for at least 2 hours or travelled less than 3 km at low speed. Since air temperature has a significant effect on tyre pressures, the recommended rule is to always check tyres in the morning or in the shade before rising temperatures or radiant heat can affect pressures. Tyre pressure can change approximately 7 kPa (1 psi) for every 5.5°C (approx) change in tyre temperature. It will go down with lower temps, and up with higher temps. Additionally, tyres lose as much as 1.5 psi per month as air escapes the tyre and rim naturally.

If tyres are inflated to placard pressures when they are hot or in the heat of the day, cold pressures will probably be dangerously low the following morning. Alternatively if a tyre is inflated to say 40 psi on a cool morning of 12°C and a day high of 32°C, tyre pressures after driving, can possibly exceed the tyre’s maximum rating

Guide To Adjusting Tyre Pressures
Speedometer Accuracy

Interestingly this is from the Queensland Police web site


Quote:
"Manufacturers place a plate on a vehicle to indicate that it complies with Australian requirements for vehicle safety, standards, Australian Design Rules, etc, and as such the requirements for accuracy of the speedometer is disclosed to the public. If an owner changes the configuration of their vehicle which alters the required specifications, it is their responsibility to ensure they have a way of knowing the correct speed of their vehicle.

The Australian Design Rules are available on the internet for people to ascertain the permitted tolerance for their car. The compliance with the design rules ensure a driver will not exceed the QPS tolerance levels if they stay within the speed limits according to their speedometer.

There are various ways a motorist is able to check their vehicle's speedometer for specific accuracy or gross error. A person can request a check via RACQ/motor repairer, a GPS device, and Department of Transport and Main Roads roadside speedometer check points (time over distance based)"
Note:
You can check your speedo error using a GPS device...But don't rely on it as a defence in court....Speeding is an "An absolute liability offence - one where the prosecution only needs to produce evidence of what someone did . What the accused believed is always irrelevant".
Another interesting thing is that what we mistakenly assume as an allowable speed limit tolerance before an infringement is recorded is not an allowance for speedo error or how much you can legally exceed a speed limit by. It is a police speed detector accuracy allowance.
Quote:
"Deduction from the speed reading displayed by prescribed speed measuring devices, This is to avoid contested cases where the only argument in court is in respect of the ability of the police device accurately to measure speed down to the last 1kmh."
Taller tyres will alter your speedometer accuracy. Queensland Light vehicle modification
This is worth reading  Speedometer inaccuracy, Radar tolerances and the Law
Avoid traffic infringements and hefty fines  Check your Speedometer Error

About Tyre Pressures

The recommended Cold Inflation Pressures listed on the vehicle's placard are ok for most driving conditions with the recommended tyre sizes. If your vehicle is lifted and equipped with larger and probably wider tires the vehicle's weight distribution is different and the recommended placard pressures don't necessarily apply. There are several methods of determining tyre pressures for load and driving conditions see the Tyre Pressure Guide


Pressure Conversion Table 
BAR PSI BAR PSI BAR PSI BAR PSI BAR PSI
1.30 17 1.90 27 2.60 37 3.25 47 3.95 57
1.35 18 1.95 28 2.65 38 3.30 48 4.00 58
1.40 19 2.00 29 2.70 39 3.40 49 4.10 59
1.45 20 2.10 30 2.75 40 3.50 50 4.15 60
1.50 21 2.15 31 2.80 41 3.55 51 4.50 65
1.55 22 2.20 32 2.90 42 3.60 52 4.80 70
1.60 23 2.25 33 3.00 43 3.70 53 5.20 75
1.70 24 2.30 34 3.05 44 3.75 54 5.50 80
1.75 25 2.40 35 3.10 45 3.80 55 5.85 85
1.80 26 2.50 36 3.20 46 3.90 56 6.20 90
Tyre Pressure Monitoring System

WK2 Grand Cherokee TPMS sensors operate on 433MHz. Although 315 MHz and 433 MHz sensors are identical in size and shape,  315MHz sensors are not compatible and are not interchangeable. TPMS sensors are designed for original style factory wheels, SRT8 sensors should not be used and are a different part number. Be sure of TPMS operating frequencies before ordering aftermarket sensors. TPMS service (mounting) kits should be used if sensors are removed and reinstalled.

  Sensor - 433MHz  (includes sensor, cap and mounting nut) 56029398AB 
  Module, TPMS 56029401AH
  Cap kit (includes 5 black caps) 68058768AA
  Hardware kit, mounting (includes black rubber valve stem , cap and mounting screw) 68058766AA
  Hardware kit, mounting (includes nut, washer, cap, seal and valve core) 68020719AC
  Valve core kit (includes 5 valve cores) 68058769AA

Modified Table from : www.wk2jeeps.com

All TPMS senders are the same (except the SRT8) for all pre 2017 WK2 models and many other Chrysler models as well. The WK2 GC  programmed warning thresholds are the same regardless of wheel or tyre size, so reprogramming is not necessary. TPMS sensors in the new wheels register after about 15km. There should be no problem as long as (Mopar) Jeep TPMS sensors are used.

The new Trailhawk has a different part number to the pre 2017 WK2 models and the 56029398AB sensor does not register with the TPMs system...The new part number is 68313387AB - 001:



Note:

Pressure will vary with temperature by about 10kps (0.1 bar or 1.45 psi ) for every 10°C change. If temperatures drop to 0°C or lower tyre, pressures should not be increased or If the ambient temperature rises to about +40°C  tyre pressure should not be lowered. As the vehicle is driven, it is normal for tyre pressures to increase with tyre temperature buildup, and should be not readjusted until after the vehicle has not been driven for several hours and away from the effects of outside temperatures or direct sunlight. For driving conditions see: Are Your Tyre Pressures Correct?

Bull Bars

Front Plastic Shroud Potential Problem




The OE plastic shroud retained when fitting the ARB bar can crack as shown and if hit hard can bend up and jam the fan. Recommended that it be replaced with either the UNeek Front Bash Plate or the Chief Products Sump Protection Plate



Have a WK2 without Parking Sensors?
 
This is what I installed and works as specified but only has 4 sensors whereas the UNeek bullbar has options for 6..I would have preferred to fit 6.

Quote (from Car Accessorys):

"So you're wondering which is the best Parking Sensors, to buy? As always OEM Technology has been put to the test, the car manufactures do a lot of research into the Reversing Sensors they will be Installing. Hence why we recommend the Ultra Sleek parking Sensors for (Reverse Parking Sensors and Front Parking Sensors) By Car Accessorys.  Because it is an "OEM Product." Most Reversing Sensors are not OE standards & are not even close to OE Standards Car acc & Ultra Sleek Parking Sensors is the only system fitted after market that will control front Parking Sensors with a left and right bar graph and also a measurement in the center of the screen to tell you how far away you are from the obstacle Automatically.  Front Sensors detect objects within 1000mm of the vehicle and will stop you at 300mm.
Reverse Sensor kit will turn it self on via engaging reverse gear and start detecting distances.
Car Accessories Provide a range of different Quality Reversing Sensors & Parking Sensors. Each system should be specific for your needs, All sensors are colour matched and flush mounted. And cover our Life time warranty on Installations."

Have a diesel without a snorkel????

Caution:

Important Air Ram Notice
(extract from Airflow snorkel documentation)

Do not turn the Air Ram away from the direction of travel because it will lessen the positive pressure necessary for proper operation. In extreme situation, at speed above 25km/h a vacuum may be generated causing irreversible engine damage The Air Ram should only be turned backward in very heavy weather/dust conditions. In which case, the vehicle speed SHOULD NOT EXCEED 25km/h as it may damage the engine. 


Travel safe with a cargo barrier!!

Off roading you will need most if not all that gear you take such as camping gear, tools and supplies. Of course we often take more than we need but all things going good it all stays where you stored while travelling. Sadly it doesn’t need an accident to shift it. Simply braking or travelling over rough dirt roads or extreme track can fling your cargo into the passenger area causing serious injury or in the event of an accident, potentially death. If you’re heading out on tour you need a cargo barrier to keep cargo  cargo area where it’s meant to be

Read more: http://www.toughtoys.com.au/4wd-touring/cargo-barriers/#ixzz4ZInVGe8k


Pet/Cargo Barrier for Jeep Grand Cherokee  WK2 (2011-2013)


Need a swing-away spare tyre carrier??

Annoyed with the idea of having to unload all your cargo by the roadside just to get to the spare under the cargo compartment floor and then having to reload it??..Maybe a swing-away spare tyre carrier is the solution.


Note:
The Formula Offroad tyre carrier (1 hour bolt on) for the WK2 some trimming to the rear bumper may be needed. This is probably not necessary but   handy to know in case: 


Have you power chipped your diesel??

If you have then maybe you should fit an Exhaust Gas Temperature (EGT) monitor. Modifying a turbo-diesel for more power with diesel power chips or modules, which function by increasing fuel delivery at full power, can generate higher than normal EGT. For the safety of your engine find out the Air Fuel Ratio (AFR) of your engine before modification A low AFR (rich mixture) can cause excessive engine heat and smoke while a high AFR is lean and clean. Always check how a performance tune or chip achieves it's power gain and what changes to the AFR are made. Few things will damage or kill a diesel engine faster than excessive EGT.

How Turbochargers work
Further reading: ETG
Further reading :AFR
Australian supplier of ETG gauges for diesel 4x4 vehicles: ThermoGuard
Universal Car Pyrometer EGT LED Gauge: EBay
EGT Probe Installation:TheSensorConnection

Jeep Grand Cherokee Performance Chips & Programmers


4X4 Off Road Insurance

Are you flushing money down the loo? - Unsealed4x4.