ITB & ITC cars are not allowed to run 7" wheels.
They are restricted to 6" wheels.
BTW, good, strong, quality, lightweight 13x6 wheels ARE getting harder/expensive to find!!!
I suspect the small-bore prod cars have the same problem (most Spridgets are limited to 13x5.5)
[This message has been edited by Greg Gauper (edited November 05, 2002).]