Hi all. I have been offerred a sweet deal on a set of wheels, however thee wheel size is 20 inches with 245/35/20 tires. I have done some research and I found out they fit, however I do not want to put to much strain on the drivetrain. I went to http://www.miata.net/garage/tirecalc.html to calculate the wheel size and this is what it revealed with those specs



Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
215/55-16 4.7in 12.7in 25.3in 79.5in 797 0.0%
245/35-20 3.4in 13.4in 26.8in 84.0in 754 5.7%

would this difference be harmful to the car

 

Difference can't exceed 3% or you may harm the Quattro.

 

If you're really dying to get those 20" wheels, you can make it work...

Just remove the tires and run straight on the rims. The ride will be only slightly harsher than you'll get running 20" wheels on an A6 with properly sized tires.

 

I believe that only applies if you tried to mix sizes. I ran a set of 20"s on my car for a week or so and it was actually not bad. the ride was still decent, but the spedo was off by about 8 - 10 mph. Nothing that Vag-com can't fix. I now have some 19" wheels that i really am happy with.