quattro allowing different roll diameter

[SeanDub]

And spares are meant for temporary, short distance driving.

[MC Hammered]

Every tire shop recommends that you buy 4 tires when replacing tires on an awd car.

Understood.

But how many people actually do that?

[bloodredsmurf]

I understand just cause one person does it doesn't mean it's the right thing, but if they're doing it, that means that the diff is allowing the difference. Obviously I don't want to kill my diff and obviously I'm not going to be doing auto cross on this while at this height and with stretched tires like those, but for "normal" driving, will I be fine? Many people run staggered for a long time and have zero problems, just want to know if my setup will fall within the "expectations" of the diff.

[SeanDub]

Understood.

But how many people actually do that?

When I was busting tires, almost all of them. I'm sure some don't, and for all I know nothing bad happens, good question for someone who works at an audi dealer.

[bloodredsmurf]

Btw my difference would be 1.2%

[aar0n.]

Just run staggered wheel widths with the same tires all around or same width wheels with staggered offsets.

Again, show me where it says Quattro allows for a 3% difference in rolling diameter because that is simply not the case at all.

Yea, pretty much. It can cope with treadwear differences of 4/32, but that's about it. Since its torsen based, there isnt much room for difference at all.

Once more since this seems to have been overlooked by some

[AUDIous]

torsen differentials are actually pretty forgiving with rolling diameters, i wouldnt go too crazy with the differences though. i work at an audi dealer and i have never seen rolling diameter differences cause diff problems. it could cause esp problems if your car has that. i run 18x9 & 18x10s with 215/40 and 225/40 tires on my b5 which is the same percentage difference your looking at. in my opinion you will be fine obviously others will disagree.

[bloodredsmurf]

I have the newer style b5, so I do have ESP, might have to leave that off. We'll see how everything turns out. I'll be sure to post a build thread or just pictures of the car once it's finished. Wheels should arrive next week. Coils tomorrow and other various items throughout the month. I'm in college trying to do what I can during the summer. Thanks for the help guys

[P78]

Wrong wrong wrong!! Quattro allows for 0% difference in rolling diameter front and rear. Haldex, which is used in R32s and TTs, allows for up to a 4% difference but Quattro does not.

this

[Tuck&Poke]

torsen differentials are actually pretty forgiving with rolling diameters, i wouldnt go too crazy with the differences though. i work at an audi dealer and i have never seen rolling diameter differences cause diff problems. it could cause esp problems if your car has that. i run 18x9 & 18x10s with 215/40 and 225/40 tires on my b5 which is the same percentage difference your looking at. in my opinion you will be fine obviously others will disagree.

That doesn't make much sense. Think of how torsen awd systems work. Its purely mechanical. There are no clutches and no liquids (minus the gear oil). The transfer of torque is cause by binding of the gears. If you run different rolling diameters those gears to a degree are constantly binding. Not something I (and apparently audi) is comfortable with. I didn't pull the 4/32's dimension out of my ass, that's what Audi themselves say. Is it possible its a conservative figure? Probably. Do I want to find out? No thanks.

Other AWD systems allow for more difference, like Porsche's visco-clutch system. Our turbo S has a 2.9% difference in rolling diameter and its fine. Haldex is about as forgiving as Porsche's system.