Since Jamo has purchased his Avon's and reports they fit nicely a slight "thread jack" to ERA and Avon seems reasonable at this time.
The Goodyear slicks are, in theory, the same size as the Bill Boards, but in fact they ARE slightly larger front and back. To gain clearance on the rear I had to raise the ride height a 1/2" and cut down the inside fender lip. The fronts, sure enough, defintely rub more than the Bill Boards did, not bad enough for me to worry about. But the Avons, which are even bigger, could be a problem all right!
I'll have to carefully consider my options, those Avons would be nice! Perhaps I can raise the ride height a bit, cut out that header vent hole, put the screen cover for the hole on the header side, cut down the lip and they might just work....