DaveOther cars in ITB are receiving an advantage now as I am runing 20# wheels and more than 50#over weight.
Wait a second. I sympathize with your need to purchase new rims however that statement a bit funny to me. First, you're being moved from a class where the car in a competitive field has absolutely no shot at winning. Now you're moved to a class where you're in a MUCH better position even with those wheels and weight. You also need to keep in mind that you are choosing not to purchase rims. It would be similar to me complaining that almost everything with my car had to be custom built. I can either choose to use the original equipment (Shelby = 6" rims, right?) or spend the money on other better options.

During the ITB impound I pointed out to Jake the Sabb and implications of using fender width to determine maximum wheel sizes. The front fenders (the rear were tweeked a bit) could easily be an additional 3" inches wider than it was. Using the chalk method and with decent tire pressures, I wouldn't be totally surprised if it were an additional 5"s. (It has Hoosier 225s) I also looked a Volvo, plenty of room there too.