richDDT

My friend is trying to sell me a set of 265/35r20 from his A7 as he is upgrading to 21" , would they fit okay on the a4? or would I need spacer?

volcomic

You definitely would not want to run a spacer assuming you're talking about the 20x9 et37 A7 wheels. Anything lower than et37 with a 265 tire will be close to touching on the fender. Should be fine on the inside. If it's your buddy selling them, why not throw one (or all of them) on to test fit?

Glisse

You would have to change the tyres - need a 265/30x20 tyre on a B9 A4, otherwise should be okay. The OEM B9 20" wheel is 9x20 ET35, with a 255/30 tyre. Pretty close - geometry looks okay in terms of rolling circumference, clearance, and scrub radius. On an A4, there is no concern with brake clearances.

Go here to work this stuff out yourself:

https://www.wheel-size.com/size/audi/a7/2017/
https://www.wheel-size.com/size/audi/a4/2018/
https://www.wheel-size.com/calc/?whe...cl=50mm&sr=0mm

volcomic

Ah, yes. I missed 35 in the tire size he mentioned. Somewhere in another thread he mentioned he's on the non-sport suspension so the 35's may actually fit, but they're going to make the car even taller. It'll also throw off the speedometer by about 3.8%.

munsabin

I would also consider pot holes in your area. I know as soon as I put my 19s back on for the summer the ride comfort is going down a bit. I would never put 20s knowing some of the potholes and road ondulations in Toronto.

audi8k

I think it's actually more than 5% difference (a bit depending om what 'standard size" you compare to).
Unless you already have subtracted the (from my experience) 1.5 to 2% built in bias in the speedometer.

Turboale

So, I have a unique one for you guys...
Any chance a 245/65/17 would fit under an Allroad? I'm currently lowered 2.2in on 245/35/20s with no rubbing. The difference in tire diameter is 2.7 but only half of that will be up correct? The difference in sidewall is 2.89in but the wheel is 3in smaller. Width is the same... I'm thinking the only concern would be the front and back of the fenders. Am I missing something? I did find a company that makes spacers if I wanted to go up another .5-1in.

richDDT

Was going to do it, but thought it would save me a good 30 mins, and not having to ruin his tires...

Turboale

why would it ruin his tires? 30min seems worth it to see if it is exactly what you want. If it is a decent enough deal you can always resell them for what you paid if they don't work or aren't worth your time.

This site is great at comparing two sizes. Does all the math for you...
https://www.tacomaworld.com/tirecalc

volcomic

You're correct in comparison to the stock 17" wheel/tire combo on 225/50-17 tires. Compared to the optional 18" wheel/tire combo on 245/40-18 tires it's actually even worse at a 6.2% difference. The 3.9% I was referencing was the difference between the 265/35-20's that come on the A7 wheels, and 265/30-20's that would fit a lot better on the B9 A4. Ideally you'd want to run 255/30-20's for a minimal 1.2% difference. Sorry for the lack of clarity.