A couple of other things to consider-
I am running 18X8's with 245/40 rears and 225/40 fronts. This is for street use. I kept my 15X8 1/2's for autoX if I start up again. I run 225/45's for the autoX. The rotating weight is much higher with the 18's. But I do like the look for the street, and they do fill up my fender wells pretty well. They do raise the ride height some, but this may not be a bad thing for the street. With the Tokico springs and the 18's, the rocker height is 7 1/2" behind the front wheel, which is about 3/4 to 1 inch higher than it would be with 195/60-14's (stock). This also raises my f-body LS oil pan about an inch. While the extra clearance is not needed for racing, the 18's give me a much improved speed bump/oil pan ratio.
Also, for what it's worth, I haven't rolled the fender lips, and I run a 1/4" spacer in the front only because my center caps are not deep enough to clear the dust covers.
Mike