Hi Kevin,
"Is 215/45/17 wide enough for the front ????"
My first answer was..no, not unless you want to have some semblance of a turning radius...but realistically, I guess it all depends on your model of GT40.
I tried the 235/45/17's first and they scrubbed the well, but ending up with the 215's only lost 0.8" of tread width (7.9" vs 7.1" or 10%), of course, the 15" Goodrich tires are somewhere closer to 9". I also want to be able to find tires for the car in a few years, and with everything going to 18's and 19's and more, I thought that it might soon be difficult. Also, the S speed rating (112mph) bothered me a little bit....and I thought it maintained the classic GT40 look with a contemporary slant.
Here's mine with 15's: