245/40/18 Tyres

[JampoTT]

Will this make any difference to handling / speed reading / acceleration or will it be negligible?

Being offered a good deal - some new 18" wheels, complete with these tyres (Toyos)... Its a LOT more money to get 235/40/18 Goodyear F1s.

[shineydave]

the 245/40/18 is 2.5cm bigger around the circumference so the acceleration would be reduced ever so slightly, wouldn't have thought you'd notice it actually.

245/40/18 - 205.3cm circumference
235/40/18 - 202.8cm circumference

if my calculations are correct the speedo would underread by about 1.2% but to be fair mine overreads by 10% anyway from the factory so again, not an issue.

[CliveH]

Some observations/questions :-

Wider tread (10mm per wheel) = better grip but more drag?

Slightly higher profile (4mm according to my calcs) = slightly softer ride??

Just tell me to shut up if I'm talking

[razor]

I am assuming that the OEM alloys on the S4 B6 are 8.5x18. Fitting 245's to your car may introduce tramlining and limit the ability of the car's handling characteristics.

[CliveH]

The OEM Ronal alloys on the S4 B6 are 8Jx18 (standard tyres 235/40)