Corey S

No matter what wheel size you run, the widest tire you can fit under the S4 fenders are 255's. Notice I said "under". You could always run wider tires and have 'em stick out beyond the fenderlip, but you'd have to run 1500lb springs to limit the suspension travel so the tires don't tear up the fenders.

The biggest setup (without MAJOR fender mods) that I've run is 18 x 8.5 wheels with a 36 to 38mm offset, with 255/35/18 tires. This will still require quite a bit of fenderlip rolling in the front, and no mods in the rear.

You might be able to run 18 x 9's with the same tire size, but then I'd recommend (although I've never tried it) an offset somewhere between 29 and 32mm.

All the other folks are right in that you should run the same diameter tire front and rear (doesn't have to be the same width). Although, the only logical stagger is to run wider in the rear, but why? The S4 already understeers a lot, so why have less grip in the front? I'd highly recommend just using the same width wheels and tires for both front and rear.

Now, if you're talking about under the RS4 bodywork, then it's a whole different story. :-)

s4wood

I am running 245/35/18 Toyo T1-S w/18x8.5 ET35 rims...very tight

Andy Hedin

Or is the rolling diameter for a 245-35-19 close enough to a 235-35-19 that it's withing the tolerance of the Quattro system?

x-ricer

it's only off something like less than 2 mm.....which is no prob for the quattro system

Žob

It's not like the car is rear wheel drive and needs more traction in the rear. There is simply no benefit and then you can rule out rotating tires...