Date Registered: 06-2017
Location: Canberra, ACT
TOTAL POSTS: 185
Re: Tyre damage on T31 AWD
Strangely enough, 'AWD' with ECU/TCU works differently to the old theory of same tyres per axle, which was due to LSD, Diff locks, and getting a car to drive 'straight'.
With an All Wheel Drive, if you have mis-matched tyres, the ECU/TCU actually throws less problems when worn tyres are on one side of the car. The ECU just thinks you're constantly going around a curved road with the 'inside' wheels spinning slightly slower. The real world problem with this, the car DOES actually steer crooked and no wheel alignment is going to fix it. So while it solves the 'computer' issue, it creates a driving issue
If you put different size tyres on axles front to rear, the ECU/TCU can't calculate why the front to rear axles are going slower/faster than each other, and starts throwing codes that there must be a malfunction in the AWD system. So while the car drives well, the computer could throw 'false' codes if there's enough difference in size.
But I don't think there would be enough rolling diameter difference between a new tyre and a half worn tyre of the same type and size, for it to create a problem with the ECU/TCU. Maybe if they were 90% worn, or were slightly different sizes?
For example, if you have a 'space saver spare', is it exactly the same size as a new, half worn, or fully worn out tyre? It has to cater for all of the previous scenarios.
Then there's also the ADR/Laws which state "The higher performance tyre must go on the rear". Absolutely stupid rule, as it doesn't take into account Front wheel drive or All Wheel drive vehicles, where you WANT the higher performance tyre on the FRONT.
My standard advice when I was in the trade:
What's your spare like (if a full size spare)
- Put two new tyres on the front, (using the unused new spare if it can be)
- Best two of the other three on the rear
- Worst tyre to spare.
Last edited by Wiz Au, 8/Dec/2017, 1:19 pm
2004 T30 series II, Ti (now sold)
JRR50 Pathfinder, QD32ETi Turbo Diesel, with 'lots o fruit'.
2012 Jeep Cherokee KK CRD Limited is current ride.
Will be looking for a white or silver 2011-2013 T31 TL (Diesel) to "pimp out".
8/Dec/2017, 1:18 pm