I don't think MT makes a 255/50 R15, mine are 255/60 DR's. These are mounted on a Weld 15x8 rim. Traction is great, I have 60' 1.58 and gone 10's with a soft launch. Here are some pics:
The wheels are 15x8, the BS is 4.5" and I used a 1/4" billet spacer to pull the tire away from the frame rail. This setup will not scrape/rub the fenders regardless of your ride height.