Tyre Help

[pat27pat]

My A8 3.0 sport is fitted with Michelin Pilot sports 6.5mm and i have a non repairable puncture.The only tyre I can get at short notice is a Dunlop can i fit that or will the differant brand mess up the Quattro?

[nicktowe]

I have the same problem but my tyre is a dunlop which has just been discontinued. The handbook says that on a quattro you have tio have the same type of tyre on each corner, and by the same they mean tread pattern, compound, etc.

A pain in the neck. It looks like i have to replace 4 part worn tyres all because of a puncture in one tyre.

[Dr G]

Nonsense, phone your local part worn people.

Would give you the details of my man if you were closer, can source most things next day.

[hman]

made no difference to my torsen diff'd quattro (same as A8).

dont worry about it

[nicktowe]

My car is still under warranty, wouldn't want to void that by ignoring the manual and the dealer

[hman]

ha!

What you are basically saying is that if you get a puncture at any time after a brand new set of tyres has been put on then you cant fit your spare tyre as the tread depths will be different. Twoddle.

Seriously it doesnt make any difference to the quattro system, believe me they are practically bullet proof - 198000 miles on one of my torsen diff'd quattros with most of its life wearing 4 different tyres with 4 different tread depths.

If they were so concerned about this then they'd have to recover you back to a dealer every time you had a puncture to fit 4 new tyres so that you didnt breach their warranty terms.

[nicktowe]

hman said:

ha!

What you are basically saying is that if you get a puncture at any time after a brand new set of tyres has been put on then you cant fit your spare tyre as the tread depths will be different. Twoddle.

Seriously it doesnt make any difference to the quattro system, believe me they are practically bullet proof - 198000 miles on one of my torsen diff'd quattros with most of its life wearing 4 different tyres with 4 different tread depths.

If they were so concerned about this then they'd have to recover you back to a dealer every time you had a puncture to fit 4 new tyres so that you didnt breach their warranty terms.

No I am not. What Audi say is that different tread patterns and compunds affect grip more than just tyre wear, and this difference in grip cfan wind up the transmission. (How that works with diffs in the system is beyond me). But its what Audi says.

I can just imagine having a drive train issue and going to Audi to get it fixed under warranty and hearing the words "sorry sir, you are not covered because you have mixed the tyres on this car agisnt the guidance in the handbook and advice from your dealer"

So for me, whilst I have a warranty, its follow the advice, new transmissions are not cheap!

[hman]

nicktowe said:

hman said:

ha!

What you are basically saying is that if you get a puncture at any time after a brand new set of tyres has been put on then you cant fit your spare tyre as the tread depths will be different. Twoddle.

Seriously it doesnt make any difference to the quattro system, believe me they are practically bullet proof - 198000 miles on one of my torsen diff'd quattros with most of its life wearing 4 different tyres with 4 different tread depths.

If they were so concerned about this then they'd have to recover you back to a dealer every time you had a puncture to fit 4 new tyres so that you didnt breach their warranty terms.

No I am not. What Audi say is that different tread patterns and compunds affect grip more than just tyre wear, and this difference in grip cfan wind up the transmission. (How that works with diffs in the system is beyond me). But its what Audi says.

I can just imagine having a drive train issue and going to Audi to get it fixed under warranty and hearing the words "sorry sir, you are not covered because you have mixed the tyres on this car agisnt the guidance in the handbook and advice from your dealer"

So for me, whilst I have a warranty, its follow the advice, new transmissions are not cheap!

You dont get transmission wind up on an audi quattro, the centre diff may run more than if you have all four tyres matched but believe me your tyres won't wear at the same rate front to back so if you look at it your way you are stuffed whatever you do.

Seriously you wont damage the transmission and audi will not void your warranty becasue you used a different tyre.

Compounds and patterns dont really come in to the equation its the rolling radius which makes the diffs run more and they are bullet proof on audis anyway as my previous post told you.

FFS do some googling on the subject before coming on here quoting your audi handbook.

And trust people who know and have experience.


From t'internet ( yours is Constant 4wd with a centre diff)


"When a 4WD is travelling in a straight line all four wheels rotate at the same speed, but during cornering each wheel travels at a different speed due to the radius of the turn. All vehicles have a differential on the front and rear axles to allow the wheels on the same axle to rotate at a different speed. Constant 4WD’s have a central differential fitted to allow for different speeds between front and back wheels, but most part-time four wheel drives do not.

When a part-time 4WD (without a centre differential) is in 4WD an attempts to corner on bitumen, all wheels need to rotate at different speeds, but without a centre differential they cannot. This creates the phenomena called "axle windup" or "transmission windup". High strain is placed on the drive shafts and transmission, eventually causing one of two things to happen. Either one of the wheels slips or spins to overcome the stress or the drive-shaft/transmission breaks. This is why part time 4WD’s should never select 4WD on bitumen.

Constant 4WD’s have a central differential within the transmission to overcome this problem."

[nicktowe]

I bow to your knowledge of 4wd, but if audi specifically say to use the same tyres I am still at risk under the warranty.

As it happen the tyres on all four corners wear pretty evenly, although i do swap front to back at about 12000 miles. When I changed the first set there was less than 1mm difference in tread depth across the 4 tyres.

Now if you are absolutely convinced, then maybe you could put up a bond for the cost of a new tranmission. Bond to be repaid whjen the car is 6 months out of warranty. If the transmission fails then i get to pay for repairs out of the bond if Audi won't honourt the warranty. Seems fair to me.

[thebirdman]

Hi, what Audi is saying is absolutely correct (technically speaking) though i think we need to remember these are motor cars and not aircraft. I think it is probably more a case of keeping all the wheels and tyres the same or very similar overall height, ie, not to upset the balance, one brand new tyre can stand quite a bit higher than say a half or two thirds worn. Also there can be a difference in aspect ratio of a tyre from tyre maker to tyre maker even thouh the nunbers are the same. Try putting some wheels/tyres side by side & see!!.

[nicktowe]

This what Audi customer services have said.

Thank you for your email of 23 February regarding the tyres on your vehicle.

I have spoken to our Technical Support Team who have advised that on each axle the tyres should be the same make and profile. They should be within 1mm of tread depth difference on each axle and within 2mm tread difference on opposing axles.