probs a daft question but I have the stock 17 sti alloys on a blob
as current they have 225,45,17 tyres whats the max width and smallest side wall size I can use?
car has not been lowered
I fancy using wider rear tyres, can this cause any affects?

 

Knackers the centre diff unless the overall diameter is the same at both axles.

You could fit a 235 tyre, but it won't be the same diameter as a 225, even if you drop to a 40 profile...

dunx

P.S. 215/45-17 is the same diameter as a 235/40-17 for a Toyo R888.....