jweier

Hi - Over the weekend I got a flat that is unrepairable. So, this morning I went to a tire shop that I have used a bunch and really trust. I was expecting to pony up for 4 new tires but the owner said I could just replace the one tire. I mentioned that my Q3 is AWD and he said that Audi is the only AWD system where you can replace a single tire. He also said that with Audi AWD you could run four different tires if you wanted without issues.

I'm very skeptical and conflicted because this shop has always given me good guidance but this seems to fly in the face of everything I can find. Has anyone ever heard this before? I'm leaning towards just getting the 4 new tires so I don't cause bigger issues.

-Jay

jweier

I called back and asked him where he got that information and he said from the Audi dealership. I also looked through the owner's manual and couldn't find anything stating to replace all 4 tires. This was so much easier when I was just ready to buy all 4!

uberwgn

Jay, completely wrong. Audi has fairly tight tolerances when it comes to replacing a single tire.

How many miles on this set of tires?

jweier

Thanks for the reply. They have ~17,000 miles so they’re probably 1/2-2/3 through their life based on my previous pair.

uberwgn

I just looked at the Owner's Manual for a 2018 Q3. The info in that book was on Page 173 -174.

If the tires are half way through their life, probably less than ideal to add a brand new tire with full tread depth. Tire Rack can shave tires.

SSA6

I had this same issue with my 2018 Q7 and just yesterday with a non-repairable flat on my 2021 Q3. From my Q7 experience I was told from my Audi dealer (and Tire Rack I think) that if the tires are within 4/32 of each other the quattro system will have no issues. 3 of my Q3 tires are at 9/32 and the replacement tire I'm buying is new at 11/32 - so no issues. This is just about the same scenario and measurements I had with my Q7 back in the fall and ran a single new tire with no issues. Good luck.

Rich807

IMO what's in the manual here on this topic & what dealers are saying is unwarranted / very overly cautious, really more of my as well tell people they need new tires as it not only doesn't cost us but in fact makes us money type of deal. Just like I run a tire size on my BMW that BMW & every major tire retailer says I can't / shouldn't do.... been running similar tire/rim ratio on other cars my entire life with zero issues & my choice of tire/wheel combo yields me more happiness with my cars.

Do what makes sense for you. If you want new rubber on all corners, then pop on some. If the other 3 tires look good & you want to put 1 new one on with those other 3, go for it.

Due to the global litigious world we live in nowadays all entities just default to the absolute most conservative guidance they can in order to stave off bitches/lawsuits from customers on the take. It's up to us to wade through that 'padding' & decide what makes sense for our budgets, wants, &/or needs.

TurboBlue5150

Keep in mind the Q3 does not have traditional "Audi Quattro" it has a Haldex system.

Not sure if that matters, but what may be true for a Q5 / Q7 with traditional Quattro, may not be true for Haldex.

findalex

Very good point. The quattro in longitudinal engine (e.g. A4, A5, A6, etc.) used an always connected torsen center differential. Later versions added clutch packs to improve fuel efficiency. The earlier versions without the clutches seem to handle wheel size differences better as the gears just rotate if there's a diameter difference. The torque distribution is completely by the laws of physics.

The new quattro AWD systems all use clutch packs and engage/disengage to save gas. I would guess the computer monitors the wheel speed to detect slippage and would then engage the clutches to put more power to the back.

I don't know how the computer would interpret different wheel speeds if tire sizes are different front/back. The worst case scenario is the computer gets confused and keeps engaging/disengaging the clutches and causes premature failure.

If anyone has an definitely answer to this, I would love to hear about it. I like the AWD, but don't like the fact I have to replace all 4 tires when I get a bad puncture.