Time for an update. I replaced my tires a few weeks ago with new ones that are the propper size (155/80-13). And today I started work on the rear wheel skirts. I got the passenger side complete (took me a couple hours), so tomorrow I'll fab up the drivers side skirt. Once that's done I'll remove my front air dam and install some more coroplast as a front belly pan and rear belly pan so that the air has less resistance while under my car, especially in the rear bumper. By installing the coroplast in front of the rear bumper it will block it off from being a big parachute that catches air and slows me down. I'll post pics up tomorrow when I'm all done.
In case anyone is wondering, to make my rear wheel skirts I used 5 or 6 3/8" pop rivets with washers, black coroplast, a strip of carpet transition metal, self tapping screws, and some nuts/bolts/washers that use the same size wrench as my pizza pan hubcaps.
I should note that I have now driven this car over 28,700 miles so far since I bought it 11 months ago.