Hello,
I have the 2004 A6 S-line with the 17 inch (i believe 9 spoke wheels).with 235-45-R17 on them , what is the BIGGEST tire size i go on those rims and as well what are the sizes of wheel and tire I could put on this A6. I would 18 eventually. Thanks

 

Don't know how wide you cna go on those rmis, I would not go past 245 but it does not mean you can't. it'd look funny, especially with stock suspension setup.
as for rims, Some have run 20's but think it is way too big! I run 19x8.5 Et 38, had Et 35 before. Some run 19 x9.5 in the rear with 265 tires.
My tires are 245x35x19.

 

I am currently running 19X8.5 with 35mm ET with no problems on my 00 2.7T.

OOOO

 

I would not recommend that you go any WIDER on the tread since all that will do is increaseyour cost of replacement and give you marginal (if any) improved grip. Your stock wheel is 7.5" and I do not think a 245 or 255 tire ids the ideal size forthat wheel. Stick to the 235 45 17 size. That is how the engineers at Audi designed the car. If you go plus size on the rim to 18", then go with a 235 40 18 tire to keep the roling diameter the same.If you go with a 19" wheel, then go 235 35 19 to keep the similar rolling diameter. If you have not ridden in or driven a car with 19's, I suggest you do before you spend any $$ on rims/tires in case you think the ride is too harsh. I think 18s are harsh enough, I cannot imagine how harsh the ride would be on 19's!!!

I would not change the rolling diameter of the car, so if you were asking for "bigger" meaning how much more aspect ratio to go on the tires, leave it alone.

 

Hey thanks!
I really like the RS6 18X8 rims so i think those might be the ones i get when i am ready.

 

I am going with 18x8 rims with 245x40x18's This will roll a little taller, but can the dealer flash the computer for the new tire size?

 

Try the handy tire size calculator in the attached link. It will compare the original size with the new tire dimensions and even tell you what the speedometer error will be.
http://www.discounttire.com/dtcs/infoTireMath.dos

 

I have a set of OEM 2006 A4 S-line 18 x 8, 43 mm offset (RS6 style) rims on my '02 A6. Fit great and look great...

[IMG]local://upfiles/23110/9D8497E1363748F5BD2CD81AD210799F.jpg[/IMG]

 

Not only will the ride be stiffer on 18" and 19" tires, but you run more risk of damage due to potholes. I've lost a Pirelli 17" to a pothole in Detroit and as well as an 18" Cooper. I would not go any bigger than 18" unless you don't intend to drive very much.