[DeTomaso] What is the widest wheel I can run . . .

[asajay at asajay.com]

On a stock bodied Pantera L?

It has 15x7 and 15x8 (front/rear) now.

How wide can I go in front versus how wide in the rear?
I've also read all the articles on offset and backspacing, and I'm  
still confused.  What is the real difference and what do I want in an  
aftermarket wheel to fit properly?

I'm looking at inexpensive rims for just racing.
Thanks,
Asa Jay