I'm going with an 18" wheel for winter and I'm trying to decide between getting a tire that will give me ~stock diameter and therefore greater sidewall and a tire that has the sidewall look I want yet will lead to smaller than stock diameter.

245/40-18 seems to be the standard size fitted from the factory for many cars (BMW 5 series, etc) but I wonder if the added 1/2" gap will be hideous. I'm lowered on Eibachs.

The sidewall on the 245/45-18 is hyoooge and almost as large as the stock 17" sidewall.

I don't really care about the speedometer discrepancy in going with the 245/40-18.

Opinions?