Just a quick question regarding the 18' 2007 speed3 rims. I'm looking at buying some winter rubber soon (get it out of the way now) and was wondering if I can go with a smaller size for the 18 for better traction, or am I stuck going with the standard 215/45 18. And I know I can run 17's, but I've got an extra set of rims I run for summer and the regular rims can now be used for winter. Thanks guys.