I want to downsize for winter from the OEM 235/40/18 to a 16" wheel. The closest, and suggested fit is a 215/55/16 which is almost identical. Someone local has a set of Audi rims with 205/55/16 winters on for a good price.

The diameter is just with 2% (24.9" vs stock 25.4") and I am not really all that concerned for the speedometer difference, but are there any other issues that prevent using the 205 instead of the 215?

Cheers.

 

If you're getting a good price go for the 205's. Your speedo will be off just a tiny bit (as you mentioned) and the narrower the snow tires the better your grip. More weight per square inch of rubber pushing down on the snow... or something like that.

 

Could the brake rotors interfere with the inside diameter of the rims?

 

A narrower contact patch will provide better traction in snow but the compromise will be dry road handling. A worthwhile tradeoff IMHO ... too bad 16's wont fit on my car as my B6 handled better traction with 16's compared to my B7 with 17's. Winter shoes ...

 

Summers are 18's s-line. Winters are - 205/55/r16.