Tyre Wear And Quattro System

Post by **Rottweiler1975** » Fri Jul 10, 2009 1:26 pm

Can anyone advise if there is an issue with tyre wear and the Quattro system. I was speaking with a mate who has an Audi Quattro and he told me that he had been advised that it was important to keep tyre wear within a few millimeters or you could cause damage to the Quattro system. I got in touch with Audi UK but this was the answer I got:

Thank you for your email dated 4 July in reference to the tyre wear on your Audi RS6 quattro.

For quattro vehicles, with the correct tyre pressures, the tyre wear should be within recommended limits both side to side and front to back. If a wheel is replaced after a puncture, it is recommended that the tyre wear is checked as soon as possible.

I asked them for the recommended limits but I have had no responce, pretty crap really. I asked my local Audi Service centre as recommended by Audi and they just looked at me with a dumb expression.

Can anyone throw any light on this subject please?

Post by **Rottweiler1975** » Fri Jul 10, 2009 1:40 pm

Funny, just as I put this subject on the forum, I eventuallu got a reply which is as follows:

The tyre wear should be no more than 1 mm different between left and right
wheels on either axel, and no more that 2 mm between front and rear on
either side. Because modern vehicles are balanced as precisely as possible
if the vehicle is driven for a prolong period of time with tread depths
outside of these parameters this may cause damage.

Anyone care to add there comments to this responce from Audi?

Post by **drybeer** » Sat Jul 11, 2009 3:20 pm

I had an arguement with a fellow on Pistonheads about this.

The 2mm rule was the one Audi technical always taught us years ago, so no more than 2mm difference all round.

The fellow (phumey I seem to remember his username was) would not accept this, and was trying to tell everyone that the Torsen is basically bulletproof, and would not be affected. He asked me to provide proof, and I must say I found it very hard to find the appropriate document to back myself up.

This is correct though and I would recommend sticking to no more than 2mm difference all around, as although the Torsen can cope with differences, at the outer ends of its adjustability my understanding it that more than 2mm difference takes it outside of its tolerances.

Post by **Rilla** » Sat Jul 11, 2009 3:21 pm

Its right, but its applicable for any 4x4 car, different circumferences on tyres will kill the diffs.

Post by **drybeer** » Sat Jul 11, 2009 3:23 pm

Rilla wrote:Its right, but its applicable for any 4x4 car, different circumferences on tyres will kill the diffs.

V true.

Post by **ecain63** » Sat Jul 11, 2009 3:35 pm

Yup. one way to see if your car is suffering in the Diff department is to drive it for afew miles on straight roads. Get it home and jack it up off the ground (all 4 wheels off the ground) on a flat surface and mark with tip-ex the top of each rim. Leave it for an hour or so (handbreak off and in neutral). The axles will unwind if there are irregularities in your tread depth. The tip-ex mark will rotate with the wheel and hey presto!

Its a trick we used to use alot in Afghanistan after driving across the desert. Saved the diffs alot of stress!

Post by **Rottweiler1975** » Sat Jul 11, 2009 4:40 pm

Thanks for all the info, I had a puncture on my front off side a while back and had to replace the tyre, so there is a bit of differance on tyre wear on front to front and front to back. I new nothing off this tyre wear limit and my local Audi Service Cntre has said nothing to me about this although they have checked the tyres for wear. I need new tyres so I better get this done sooner rather than later. Onc again thnks everyone for confirming this information.

Post by **jd_hants** » Mon Jul 13, 2009 10:37 am

So, correct me if Im wrong, but I assume that all the tyres 'should' wear equally so will all need replacing at the same time so shouldnt b3e a problem. However, if you get a puncture then is it necessary to replace ALL 4 tyres to ensure that they are all within spec of each other???

Post by **Daveperc** » Mon Jul 13, 2009 5:13 pm

I don't know about the "rules" from Audi, but certainly on my old V70R AWD this was a significant issue. It could cope with a small difference front to rear, but was very sensitive to side to side wear.

I did have a pucture, and replaced both tyres (rear I think) - and then broke the drive shaft within about 5000 miles - the techs took one look at my tyres and said "not surprised".

Dave

Post by **drybeer** » Mon Jul 13, 2009 9:21 pm

jd_hants wrote:So, correct me if Im wrong, but I assume that all the tyres 'should' wear equally so will all need replacing at the same time so shouldnt b3e a problem. However, if you get a puncture then is it necessary to replace ALL 4 tyres to ensure that they are all within spec of each other???

yes there are circumstances which could dictate a change of all 4 due to one puncture.

Post by **Rilla** » Tue Jul 14, 2009 8:10 am

Not quite dry beer, as long as the two fronts are same size & both backs are same size its ok, dont all have to be same size.

A difference between front and rears is ok.

Post by **drybeer** » Tue Jul 14, 2009 2:30 pm

Rilla wrote:Not quite dry beer, as long as the two fronts are same size & both backs are same size its ok, dont all have to be same size.

A difference between front and rears is ok.

but still not more than 2mm difference I'm sure...

Post by **Rilla** » Tue Jul 14, 2009 2:51 pm

erm, to the best of my knowledge difference between front and rear shouldnt be an issue as they are governed by the transfer box not a diff, so a difference in them wont affect a diff, just the transfer box which is able to deal with the difference (think about different speeds between front and rear when your drifting/sliding).

Thats how it was explained to me by a car designer for land rovers years ago. He specifically worked on gearboxes and diffs so im guessing he knows more than I ever will lol.

I personally wouldnt have an issues with running diff size circumference on front & rears, besides, my '6 seems to go thro fronts at a 2:1 ratio with the rears, so I wont be throwing a 1/2 used set of rears away when i get new fronts lol.

Post by **drybeer** » Thu Jul 16, 2009 10:01 am

Rilla wrote:erm, to the best of my knowledge difference between front and rear shouldnt be an issue as they are governed by the transfer box not a diff, so a difference in them wont affect a diff, just the transfer box which is able to deal with the difference (think about different speeds between front and rear when your drifting/sliding).

Thats how it was explained to me by a car designer for land rovers years ago. He specifically worked on gearboxes and diffs so im guessing he knows more than I ever will lol.

I personally wouldnt have an issues with running diff size circumference on front & rears, besides, my '6 seems to go thro fronts at a 2:1 ratio with the rears, so I wont be throwing a 1/2 used set of rears away when i get new fronts lol.

I thought it was the much talked about torsen (torque sensing differential) which split the power front to rear in the modern quattro system.

The older ur-quattros and some 1980s 80 quattros / 100 quattros would have had a system more like the landrover possibly back when they had a switch to lock up the diffs etc.

It is the tolerances of the torsen which i believe need the tyre treads to be so similar.

Drifting or sliding should mean the diff "unwinds" taking away any stresses I would think as the tyres are losing contact with the tarmac often, but it is the rest of the time when they are gripping I am talking about.

That being said I'm not an expert - are there any folk more knowledgable than I who can tell us if this tyre thing is correct? Griz maybe?

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