A4 Quattro System - Can I Run Wider Rear Wheels..?

Not sure but I think the main factor is the rolling radius of the wheels so perhaps if you can keep that the same (or as near as you can) then it'll be OK

The A4 Quattro is Torsen based and is full-time unlike the A3 system which is Haldex and effectively only sends power to the rear if the fronts loose traction.

HTH
Dave

re the Quattro - Macduff's right - A4 is Torsen Quattro, not the psuedo quattro (Haldex) that they put in the little Audi's.

Same again on the wider wheels: assuming they don't scrape, just remember that the profile is a percentage of the the width, so if you're REALLY stepping up the width, then you may need to reduce the profile to keep the rolling radius the same.....

use something like the Toyo site as a guide....

e.g. if you think that regular 18's are supposed to have 215/40/18's or 225/40/18.... so assuming you're going for something like a 255 width tyre (arches permitting), then you'll find that 255/35/18's are almost identical to those (and 255/40/18's are about 3% too big).

that site also gives you a guide as to what range of widths each size tyre is okay with (you could keep the tyres the same if you already have 225/40/18's since they are chunky on 7.5J's and will stretch to 9J's).

Don't forget that if you alter the offsets or widths it can effect the way ESP operates due to you moving the points of rotation.

hmmm.... probably right... best try to keep the centre-points at the same and keep the tyre width vaguely the same (205-255 range shd be fine)....

what are standard offsets on 7.5J A4 B6 wheels?