Ok well thanks for all the replies. This morning when I went home from work I checked my rear tire sizes. I have the Goodyear Eagle GT 2. For some reason I thought they were 295/60's, which would be a taller tire. Well they are actually 295/50's. I measured the tire and its roughly 26.5 inches tall. There is no way I am putting a taller tire like the Mickey Thompson 315/60 on my car. Looks like my options are either to do like Greg and put the 325/50 on my stock 15 X 9.5 rims, or go with some 17" rims with some 325's. Both these options are roughly the same height as my current rear wheel, so no need to mess with gearing and stuff.
Anyone have any experience with the trade offs of going with a bigger rim, like going form a 15" to a 17"? Logic says that straight line performance could suffer, but cornering would improve. Would that 2 inches and shorter sidewall really make that big of a difference? I really wouldn't want my straight line performance to suffer a whole lot. And then there is the whole thing with the drag radials. Say you go with the 17" rims. However, you are putting drag radials on them. Well there goes your cornering improvement! Too much unexplored ground
Also, where do you get the proper backspacers??