245 would be a car fitment. 240 is bike sizing.

 

245 would be a car fitment. 240 is bike sizing.

 

Thanks for all the help

 

I am running 235/40-R18 with Conti's and there is no problem. The speedo was always a little off and this does not make it significantly worse. I'm probably going to go with 245/40-R18s when these have to be replaced to get a little wider tire, more rim protection, and to fill the wheel wells more.

Does anyone out there know if the A6 4.2 axle is wider or is it just the body style?

 

I was told that 245 40 18 would be too tall and would rub. Anyone know if this is true

 

I ran this through the Discount Tire calculator for 235/40-R18 vs 245/40-R18 and the 245 is .4" wider, .32" taller (and this is only .16" as half is below and half above the axle), and reads 65 at 65.81 actual. I doubt the height is an issue. The width may be an issue because of the offset, but even there I appear to have at least an inch between the tire and any suspension part. And the suspension parts in question move with the wheel. Is anyone out there running 245/40-R18 tires?

 

i did 225 40 18 on mine they barely clear the top suspension tried 235 40 18 little too big mines a 2003 a6 2,7 quattro hope this helps

 

I am running Conti 235/40-ZR18 on RS4 replica rims with no clearance issues at all. Here are the specs on the rims, if that helps:
Diameter - 18";
Width - 8.5";
Offset - ET38

I'm trying to find out if 245/40-ZR18 will fit the car as the Contis will have to be replaced after this summer. This tire is .32" taller and .4" wider.

 

They will be too wide. The 40 series on an 18 is the right height.