So I know the quattro system is sensitive on our cars, a have a set of 20x9 wheels laying around, I'm thinking about putting on an 06 A8. There are two different sizes ( 275/40 n 275/35). Does anyone know if these sizes would be ok?

 

I wouldn't even remotely consider it.

 

There's over an inch difference in the diameters. That's well beyond the acceptable limit.