askered

I recently purchased a 2008 Q7 4.2 S-Line (without adaptive air suspension option) that came with 20" S-Line (5 spoke) wheels. I'm considering changing the 20's to studless snow tires, and picking up the OEM (7 spoke) 21" wheels to run as the primary set. Candidly, I think the 275/45/20 tire looks a little small relative to the vehicle size, and am wondering if I can run slightly larger tires on either the 20" or 21" wheels than what Audi recommends without doing additional mods. Has anyone ever plug-n-play fit a 285/45/20 on the 20, or 295/40/21 on the 21? Disregarding the speedo being a little off, is there enough clearance in the wheel well to accommodate these slightly larger diameter tires?

scotskier

295/35 is standard on OEM 21 inch

I also run a larger profile (265/60 -18) snow tire which has a rolling radius ~ 1inch larger without any issues

so you should have no issues with a 295

askered

Thanks for the feedback. Using the calculator at www.1010tires.com, you're definitely running a larger diameter with the 18's but what about width? I'm wondering if the extra width and sidewall height 295/40R21 has over the stock 295/35R21 and your 265/60R18 will create a clearance issue that may need spacers to correct. My plan is to order the tires online. With freight and the headache of trying to return them if they don't work, I'm hoping to hear from someone that has done exactly what I'm trying to do.

275/45R20 (Stock)
Section Width: 10.82 in 275 mm
Rim Diameter: 20 in 508 mm
Overall Diameter: 29.74 in 755.39 mm
Sidewall Height: 4.87 in 123.69 mm
Diameter Difference: -

265/60R18 (Custom)
Section Width: 10.43 in 265 mm
Rim Diameter: 18 in 457.2 mm
Overall Diameter: 30.51 in 774.95 mm
Sidewall Height: 6.25 in 158.75 mm
Diameter Difference: 2.53%

295/40R21 (The Goal)
Section Width: 11.61 in 295 mm
Rim Diameter: 21 in 533.4 mm
Overall Diameter: 30.29 in 769.36 mm
Sidewall Height: 4.64 in 117.85 mm
Diameter Difference: 1.82%

Anyone else have any feedback here?

iconoclast

stick with the overall same size diameter. if not you will have issues with speedometer, turning radius etc.

scotskier

Your call, but if you look at the overall diameter of my snow tires, which have no clearance issues even with the adaptive air set to dynamic, and that 295 section clears as standard there should not be any issues. If you look at your numbers the increased (diameter) clearance required is .275 inches (half of the difference) wrt speedo difference, it will probably get you closer to a true reading since it typically over reads. I have not seen any issues on the snow tires (and I also ran this size on my last Q which did not have the additional rack spacer that is on Qs with 20s or 21s)

askered

So does the OEM 21" have a different offset than the OEM 20"? If so, what? I guess my biggest concern is the attached image. I can get about 1.5 fingers between the existing tire (275/45R20) and this bolt hanging down in the front wheel wells. Again, jumping up to a 295/40R21 is a concern because unless the offset is different, I'm pretty sure the 295/40 tire will end up getting ground away by the bolt.

Overall I'm not concerned about speedo, turn radius, etc. There just doesn't appear to be enough clearance for the 295/40R21 because the extra 5 on the sidewall will raise the corner of the tire into the bolt. Last post, I promise. Thanks.

iconoclast

21x10 et44.
20x09 et60.

askered

Iconoclast, can I put a 295 width wheel on the 9" wide 20's or is 285 that largest I should consider? Now having second thoughts about the 21's and wonder if I can achieve a better look with a bigger tire and (possibly) spacer using the S-Line 20. Thanks!

iconoclast

295 on a 9" wheel is going to be way too much meat in terms of looks, i cannot say if it will clear or not but just on looks alone i wouldnt go for it.

9"




10"

marioec

Are those Toyo Proxes STI II on the second picture ?