What difference would fitting 245 40 17 do to a car on the rears when i normally fit 235 45 17 as an all rounder?
when i line the tyres up they look almost the same,
not much, there only an inch wider. what are your alloy? 17x8?
Isn't this a problem with quattro cars?
'04 A4 Avant 1.8T Quattro LE - Retrofitted: RNS-E, Bluetooth, front centre ambient lights, full DIS, cruise control, alcantara steering wheel, more to follow....
Gone but not forgotten - '98 A3 1.6 SE, '01 S3, '01 A4 1.8T Quattro SE, '02 TTC 225, '04 A3 3.2 Quattro S-Line DSG
if you stick 245/40/17 on and you have 17"x8" alloys, the 245 will make the tyre over hang on the front of your alloy by about 1 cm.
if you plan on doing this i would suguest you put 245/45/17 on the rear otherwise your rear tyres will have a shorter circumference and would mean your rear tyres spin faster than your front tyres which could cause problems with your esp.
i don't personally know if this messes up the quattro or not. if i had to guess, i don't think you would have a problem with the tyre size i sugested.
good luck either way.