Advice: Used RS7 with wrong tire size. Buy or pass?

[Apparition]

A used 2015 RS7 prestige popped up on my radar.

On the plus side:

Has ~2 years Audi factory warranty remaining.
Dealer is putting on brand new rotors and pads.
Has B&O stereo and HUD, two features I personally like. (I know the B&O is gimmicky to some but to my non-audiophile ears I like the way it sounds. I had it in my 2013 S6.)

So here's the catch. The car has 275/35/21 tires. Dealer has been up front about this and said previous owner did this because it rode more comfortably. My engineer brain can't get past this though. If you wanted a softer ride, do it the right way and go down to 20" wheels with the 275/35's. Equipped as is, this means a 4% error in the speedo and odometer. If this were a used A4 I probably wouldn't care, but on a car like this....

I guess I could negotiate the cost of new tires into the price but I'm wondering if driving the car with the wrong tires - even an inch taller than OEM - could cause problems down the road.

[JGood]

What exactly is your concern? The mileage being slightly off? As an engineer you should know that as long as all four tires are the same size there would be no danger to the drivetrain to simply go with a bigger tire.

[OlyS6]

How much tread is left on the tires? Might be worth replacing regardless. Certainly not a deal breaker given the kind of expense you're looking at for the rest of the car, esp if the dealer is putting on new pads and rotors, and you've got both the HUD and the B&O, which don't pop up as options very often on the used market.

[fR3ZNO]

A 4% error would mean that if the car traveled 100,000 miles the odometer would actually read 104,000 miles. Is the value of an RS7 really that sensitive to mileage that it would matter? It's not like it's a Ferrari where owners rarely drive the damn things in fear of devaluing.

[Apparition]

Thanks for the replies guys. The 4% doesn't seem like that much but to my OCD brain it's MASSIVE . Given that the air suspension can lower and raise the car just with correctly sized tires by probably an inch, it's probably not going to cause issues but it's still not an Audi approved wheel + tire combo. The tires on this particular car appear to have a healthy amount of tread so I'd be basically tossing tires with very little wear on them.

[Skyler@Achtuning]

I don't think that the diameter would cause any damage or lasting issues but if it is a concern for you I would say that it's reasonable to negotiate for a discount in order for you to have new tires in the proper size mounted.

One question that comes up when people ask about changing the overall rolling diameter with any significance is possible effects on the ABS or ESP systems. One would assume that those systems are calibrated to work properly with a specific range of tire diameters, however I suspect that only a few engineers at Audi would be able to tell you what the range actually is.

[morski]

Buy the correct size and sell these and recoup some costs. Negotiate a new set into the discount of the car price

[kjeeper10]

My speedo reads 1-2 mph faster with stock tires. You might be ok.

[NardoRS7]

I think you're overreacting... I'm actually running 285/35/21 with my car because I wanted a softer ride and more grip. I've had no issues with it and it's been almost a year. You may consider it the "right" way by going to 20s, but that involves purchasing another set of wheels.

[elptxjc]

I ditched the summer tires at 100 miles, so I wouldn't bother with tire age. In your case, I'd also swap those wheels for 20s, with the proper size, either summer or ultra-high performance A/S, like I did, to be able to use the car wherever I want, with little difference in summer grip (and a lot more grip in all other seasons), plus a lot better in the rain all the time, plus less noise too. As far as any damage from oversized tires, since they're all the same size, the car 'would never know'. The only possible issue would be tire touching fender at full compression, but really doubt it. And car is slightly higher off the ground too. To me, anything larger than 20" is completely unnecessary, and not even nice looking IMO. Plus only summer tires in that size. Good luck with the hunt.

[BATLSHIP13]

To be honest, this wouldn't concern me at all. I'm a mech E, if that helps. Also sent you a PM on my RS7 im selling ;)

[MP4.2+6.0]

No, it's not correct and I try to avoid any changes that get into actual speedo error territory, especially like this when it reads too low and maybe others may drive the car and run more risk of tickets. But besides speedo error and any risk of rubbing (which probably already happened by now if there is any clearance issue) it isn't going to "break the car" or its systems. Car will also be riding ½" higher than stock, which may be a good thing at least initially to avoid real world chin scrapes and such.

FWIW, the size is the D4 S8 OE size. ...I own one so know it. If they are quality tires, you may be able to sell used and get some value for them. Double credit if you likewise find a used set in the correct size.

[itsmatt33]

A 4% error would mean that if the car traveled 100,000 miles the odometer would actually read 104,000 miles. Is the value of an RS7 really that sensitive to mileage that it would matter? It's not like it's a Ferrari where owners rarely drive the damn things in fear of devaluing.

4k mileage error on a car that carries a 100k+ pricetag at new would be a big deal to me...

doesnt affect the car or performance in any way sure but if im buying a car with say 50k mileage it better have 50k mileage.

[fR3ZNO]

4k mileage error on a car that carries a 100k+ pricetag at new would be a big deal to me...

doesnt affect the car or performance in any way sure but if im buying a car with say 50k mileage it better have 50k mileage.

I just used the 100k miles as an example.

But I know what you mean, I'm sure I'd be just as anal about it as the OP if I was dropping that kinda coin on a new car.

I was mostly just thinking out loud earlier. Lol.

[15 Phantom S6]

A 4% error would mean that if the car traveled 100,000 miles the odometer would actually read 104,000 miles. Is the value of an RS7 really that sensitive to mileage that it would matter? It's not like it's a Ferrari where owners rarely drive the damn things in fear of devaluing.

It's actually the other way around. Since the tire is a larger overall diameter than stock (4%), then the odometer would read 96,000 miles when the car has actually traveled 100,000 miles...

To the OP, other than the wheels having a little less potential for damage and a small touch of a softer ride, no harm can be done from the tire size chosen.. In fact, if you did want to stick with 21" wheels, the ride will be better with those sized tires than the correct sized tires... I definitely wouldn't let that tire size make or break the deal..

[ProfessorChaos6]

You'll be fine. I've had cars that went through 8 different tire sizes before I found one I liked. If it's really that big of a deal to you,try to get the dealer to change them.

Sent from my VS988 using Audizine mobile app

[Apparition]

Wanted to update this thread after test driving the RS7 today.

No issues with the tires until I hit some tight curves and then, definite audible rubbing of tire on the fender.

So my opinion after driving an RS27 on 21" wheels with 275/35/21 tires is that it's a no-go.

I may pass on this deal as I'm not getting good value on my E63 in trade but I thought this information would be useful to member here.

cheers.

[Serpent]

Wanted to update this thread after testing driving the RS7 today.

No issues with the tires until I hit some tight curves and then, definite audible rubbing of tire on the fender.

So my opinion after driving an RS27 on 21" wheels with 275/35/21 tires is that it's a no-go.

I may pass on this deal as I'm not getting good value on my E63 in trade but I thought this information would be useful to member here.

cheers.

Weird, car on normal sporty ride height? either way, I hope you find another RS7 to your liking. Just as an fyi, I ran 295/35/20 on my rs7 and it was lowered on factory air and had no issues of rubbing.

[IowaRS7]

Are the 21" wheels aftermarket or stock? I can't believe one would rub with a 275/35/21 tire on stock wheels and settings, not gonna happen. Now, if they are aftermarket wheels with different offset or aggressive spacers and ride height has been modified with CETE or H&R module, then I could see some rubbing potential. Much of that is adjustable though and it would be easy to eliminate any rubbing. I have wider wheels with more aggressive offset, 285/30 MPSS and lowered quite a bit with CETE and no rubbing. Granted they are not a 35 profile tire, but even from one 30 profile tire to another, there is often variation in wheel diameter.

[Apparition]

Are the 21" wheels aftermarket or stock? I can't believe one would rub with a 275/35/21 tire on stock wheels and settings, not gonna happen. Now, if they are aftermarket wheels with different offset or aggressive spacers and ride height has been modified with CETE or H&R module, then I could see some rubbing potential. Much of that is adjustable though and it would be easy to eliminate any rubbing. I have wider wheels with more aggressive offset, 285/30 MPSS and lowered quite a bit with CETE and no rubbing. Granted they are not a 35 profile tire, but even from one 30 profile tire to another, there is often variation in wheel diameter.

All good questions. They were stock 21" and it's very possible the car was slightly lowered. Car had standard air suspension. Rubbing was unmistakable though. Salesman and I heard it loudly when attacking a hairpin turn.

Here is side photo of front of actual car. There's not a lot of clearance. I'm not an expert enough to know if this is simply the effect of the 35 profile or if there is additional lowering:

https://imgur.com/a/hYf5FDs

[IowaRS7]

All good questions. They were stock 21" and it's very possible the car was slightly lowered. Car had standard air suspension. Rubbing was unmistakable though. Salesman and I heard it loudly when attacking a hairpin turn.

Here is side photo of front of actual car. There's not a lot of clearance. I'm not an expert enough to know if this is simply the effect of the 35 profile or if there is additional lowering:

https://imgur.com/a/hYf5FDs

Hard to tell from that angle if there are spacers or not, but it almost looks like there might be. That could be pushing the wheel/tire out far enough to cause an issue. Was the rubbing on the front? If so, there is a fender screw that you can remove to help with clearance. It gives a decent amount of room for additional drop. That gap doesn't look aggressive to be honest, so pretty surprised you would be rubbing at all with that setup unless there is a spacer pushing that out farther than it should be with the 35 profile tire. The same tire on a wider wheel would stretch some and round the edges more, but on a stock wheel its more straight up and down. In either case, it should be easily remedied if there are spacers on it.

[valleywine]

Hard to tell from that angle if there are spacers or not, but it almost looks like there might be. That could be pushing the wheel/tire out far enough to cause an issue. Was the rubbing on the front? If so, there is a fender screw that you can remove to help with clearance. It gives a decent amount of room for additional drop. That gap doesn't look aggressive to be honest, so pretty surprised you would be rubbing at all with that setup unless there is a spacer pushing that out farther than it should be with the 35 profile tire. The same tire on a wider wheel would stretch some and round the edges more, but on a stock wheel its more straight up and down. In either case, it should be easily remedied if there are spacers on it.

Wondering if anyone has experience with fitting a 285/35/20 tire on 20x10 ET25 rims? Currently, I have a 265/35/20 and the gap between the top of the tire and the fender is 2-3". It looks like the tires are too small and also inset a bit. I need new tires and would consider the 285/35/20 if I knew it would fit. I understand the 275/35/20 will fit without issue, but it's only a .3" taller and .4 wider than stock. The 285/35/20 is .6" taller and .8" wider than stock.

The car is not lowered. And...…..it appears a little higher than others I've seen on the road.

[IowaRS7]

Wondering if anyone has experience with fitting a 285/35/20 tire on 20x10 ET25 rims? Currently, I have a 265/35/20 and the gap between the top of the tire and the fender is 2-3". It looks like the tires are too small and also inset a bit. I need new tires and would consider the 285/35/20 if I knew it would fit. I understand the 275/35/20 will fit without issue, but it's only a .3" taller and .4 wider than stock. The 285/35/20 is .6" taller and .8" wider than stock.

The car is not lowered. And...…..it appears a little higher than others I've seen on the road.

With a narrower tire you will have more sidewall stretching, so it’s easier to clear the fender. As you put a wider tire on the same wheel, the sidewall isn’t stretched and results in a few things:

1. More wheel protection, a 285 on a 10” wheel would be pretty good for that.

2. Better ride, the tire will be able to absorb more of the bumps on the road and aid in the overall suspension better.

3. The tire will effectively come out closer to the fender due to being more straight up, squared off vs rounded, from the wheel lip. This can help eliminate gap if you are on stock height settings, but if you are lowered you will need to watch how close you get. With a 10 ET25 you are decently flush between wheel lip and fender. At stock height you are likely just fine, probably even still room to lower via VCDS if desired.

I will also note that it depends on the tire brand and make too, not all are the same.