Howard,
Interesting timing. I called Stratton Motorsport last week. He told me I could fit a 10.5" rear wheel with a 275 tire on my Carrera bodied car for rear. He said I could do this without moving any oil lines. He also said he's been doing this for years on customer cars. I'm VERY sceptical about this. In my experience I've seen someone put a Fuch 9" wheel with a 1" spacer on the back of a Carrera bodied car with no rubbing issues.
As far as a Turbo bodied car I've seen people run a 345 rear tire on an 11" wheel. I don't know if they had to do any moving of oil lines though.
I'm currently looking into the Linsey Racing wheels in 8" by 17" front with a 235 tire and 10" by 17" rear with a 255 tire. They will cost about $1000 less than the Stratton wheels.
