Interesting enough, they are running 20" Razors on the 40th anniversary edition, though I believe the rears are only available in 10" width. From the picture of the black rim, looks like the fronts are 255/30/20 and they are Michelin Pilot Sports... EXPENSIVE tire there. I would have to assume the rears are in the 285-305 size rangeHas anyone put these wheels on a GT500? If so do you have any pics you can share and are you running the same size tire all the way around?