Question about 1 new tire on AWD

[Nickr7777]

I got a flat on my rear passenger, and replaced it with Michelin pilot sport 4s to match the other 3. The other 3 tires have about 5k miles on them so far. I didn’t want to dish out another $1300 to replace the other 3 so I tried to take it to a racing shop that did tire shaving. Well I guess he didn’t have an adapter that fit the Audi bolt pattern so he couldn’t do it. He measured the circumference and said there was about a 3/8 difference compared to the other 3 tires. Is this enough of a difference to affect the drivetrain and damage some stuff? Would I be ok driving it for now? I’m gonna try to find another place that can shave the tire to match the other 3 tires, but if I can’t would i be ok? Or would I have to buy 3 new tires? Thanks !!!!

[Fresh.S4]

i feel like i saw this situation come up last week maybe the fb page or here lol?????

you could probably get away with 1 new tire BUT id still at least get a pair of new tires to keep the fronts/ rears even.

(and this folks is why i dont believe in "performance" expensive as shit tires lol.) id rather always run cheap ones and replace as necessary to keep the balance than buying these expensive xzy superduper name brands and cost an arm and a leg everytime.

[Smac770]

It's come up more than a few times in recent months across the B8 and B9 forums here and at AW.
If the other three are similar tread depth, shave the new one down to match is the best answer. The average tread depth on the front and the rear has to be within 2mm of each other per Audi's guidelines. So if the three are the same and the fourth is 2mm more, that'll make for a 1mm more average on the axle with the new tire.
Tread depth normally starts around 8mm, replace around 2mm (1.5mm if you like it dicey). You don't say what the tread depth on your current tires are. 7mm, non issue. 6mm, just run it. 5mm, could get away with it, but you're better off finding a shaving solution. 4mm, find a shaving solution.
If you have the sport diff, make sure the rears are the same.

[Slvrbul8]

Just buy 1 more new tire and then you have a matching set. Put the new tires in the rear and call it a day.

[Smac770]

Just buy 1 more new tire and then you have a matching set. Put the new tires in the rear and call it a day.

That ignores the whole issue, and would actually make the front<>rear difference worse.

[Nillious]

This is why tire rotation is so important on these cars. I used to run fwd tires till they’re shot cause the rears last so long. I’d buy new rears and move rears to front. That way I only had to buy two tires at a time lol. Not possible with these cars.

[blackfunk]

In my experience having owned 4 Audi's in recent years is that the fronts always wear faster than the rears. Get another new tire and move both to the front and then just rotate them side to side not front to back.

[Nickr7777]

I found another shop that does tire shaving/truing so I can match the new tire to the other 3. But can’t get an appointment for two weeks. Would it be ok to drive it like this for now ? I don’t commute or anything just city driving short distance. Or would it be better to park it till then?

[Smac770]

You never mention the actual tread depth difference between your current and new tire. With only 5k on the old ones, I can't imagine the difference is so big that it'll matter for a short mileage.

[Fresh.S4]

im still tripping about this tire shaving lol....
are they mounting the tire to a machine and using some sharps to shave that 1-2mm off lol?
youtube here i come!

[JRYtheS4]

im still tripping about this tire shaving lol....
are they mounting the tire to a machine and using some sharps to shave that 1-2mm off lol?
youtube here i come!

Yes. Some tire sellers even provide it as a service when purchasing the tire. See here:

https://m.tirerack.com/upgrade-garag...drive-vehicles


Sent from my SM-G991U1 using Audizine Forum mobile app

[Smac770]

im still tripping about this tire shaving lol....
are they mounting the tire to a machine and using some sharps to shave that 1-2mm off lol?
youtube here i come!

I had a coworker with a pickup, but he always took his new tires to a shop he knew and had them shave them all uniformly to the same diameter. He hated the vibrations of "new" tires since they weren't perfectly round. Maybe more an issue with truck class tires than passenger tires.
Tirerack even offers shaving if you need a tire to match existing worn tires, though it seems they started it more for racing prep purposes. https://www.tirerack.com/search.jsp?...epth%20shaving

[jeremy@lime-swap]

OP, something doesn't add up. A new tire will have about 5/16" of tread depth. Or about 3/8". Your shop said that you have 3/8 difference, which would imply that your 3 "old" tires are completely bald. Surely, they are not after 5k miles. I doubt the difference is greater than Audi spec. And I assume eve that is very conservative. You ever steer the car? Then one tire is spinning faster than the other. This is why we have differentials.