From what I've read over and over is that tires of different tread depth and pattern can cause harm to Diffs and Transfer cases. I've always read to change tires in fours with the same tires (new). Again... this is what I've read over and over on here, I have never tested it myself and quite honestly don't want to.

 

Sorry but thats rubbish, every slight change in direction will cause the differentials to move so having tyres of slightly different wear stages wont hurt any of the transmission. Whilst the vehicle is AWD that does not mean that the connection between each drive shaft is fixed. These vehicles are not flimsy F1 carts and are designed to withstand minor changes to rolling diameters. Don't know what you are reading but obviously not written by somebody with an automotive understanding or qualifications.

 

No, do not mix tyres.

Apart from the hole in the middle of the tyre, tyre sizes are nominal and may vary in overall diameter by quite a bit.

So all four tyres should be the same size, the same make, the same model and the same tread pattern, and with no more than 2mm tread depth difference between tyres on the same axle and no more than 3mm tread depth difference between tyres on the front and rear axles.

There are plenty of owners here and elsewhere who, having reported binding issues, have fixed them after buying new tyres so all four match as above.

 

This is what happens when you never rotate. Do not mix. Buy all new. Bad for the differential.

 

This is what happens when you never rotate.

waste of money.

 

Thanks all
Have booked in for Bridgestone's all round. Appreciate your comments
Bob

 

If you are really cheap you could in theory get mismatched tires ground down to identical diameters. I still wouldn't want a mismatch because it could mess up the handling, and they could still go out of spec by wearing at different rates. I would do that if I had fairly new tires, and one blew out, and I could save the other 3 by getting a new identical matching tire and grinding it to the correct diameter.

 

I religiously rotate 5 same wheels/tyres every 10k at $50, with that comes a W.A, tpms swapped over and balanced, cheap insurance for longevity. That price is based on being a return Tyrepower customer.

 

This has been discussed so many times over the past 15 years I'm not going to bother validating it all over again.

The electronics sort out marginal differences up to 50 mph but not beyond which is one reason the spacesaver has a speed limit.

You can either stick with 4 identical tyres with no more than a couple of millimetres wear difference or not, I don't care.

The proven fact is that when people have arrived on here and elsewhere with a transmission grabbing issue and have fixed it by matching up their tyres we know the advice works.

Funnily enough even the manual tells owners to use the same tyres on all four corners and that's pretty common across other brands offering all wheel drive too.

 

No Touareg has Haldex (electro-hydraulic). Either electro-mechanical 4xMotion, or TORSEN.

Yeah I screwed the pooch on that one I was thinking my Audi. The Touareg in question is definitely torsen. Thank you for correcting that.

So your saying a Haldex can only be used in straight lines, roads without corners - I think your understanding of this transfer/transmission is wrong. If that were the case every time you hit a slippery patch where front exceeds back you destroy the transfer - load of sh!t. Transfer differentiation is designed for that reason.
My final reasoning for the unqualified is what happens when you have to fit the space saver spare, the rolling diameter is not the same as the other 3 wheels not even close, so your trans will blow 10m down the road? Go back to school and learn something.

The spare tire has the same exact dimensions as OEM

This has been discussed so many times over the past 15 years I'm not going to bother validating it all over again.

The electronics sort out marginal differences up to 50 mph but not beyond which is one reason the spacesaver has a speed limit.

You can either stick with 4 identical tyres with no more than a couple of millimetres wear difference or not, I don't care.

The proven fact is that when people have arrived on here and elsewhere with a transmission grabbing issue and have fixed it by matching up their tyres we know the advice works.

Funnily enough even the manual tells owners to use the same tyres on all four corners and that's pretty common across other brands offering all wheel drive too.

He baited me. I should have known better than to get involved, I just hate the idea of someone doing a Google searching and seeing that BS post and believing it

If I'm not mistaken, all rolling diameters of Touareg wheel combinations are essentially the same, just the rim/sidewall ratio changes. The inflatable spare is within the same rolling diameter. Further more to your "reasoning", you are not drive for long distances with the spare, or at speeds over 80km/hr; this is vastly different from daily driving at 120km/hr+ on mismatched tires.

Go back to the FSM and SSPs and learn something.

Yes 💯 every tire combination offered (at least the several I've manually checked myself) equal out to the same exact dimensions, even across euro and aus markets.

 

There is an allowable spec for tire size differences- going outside that spec can cause both damage and other issues like confusing the ABS and traction control systems, but if you stay within that spec the system can accommodate slight differences in rotation speed.

Even a fully open old fashioned differential will wear faster and heat up if you have a large tire size difference.