[LONGHAIR]

Rim off-set or backspacing is not the only factor in the larger tires. Rim width itself can make a difference in diameter. As it has been stated, the tire size printed on the tire is generally an exaggerated number. The typical 38-40-42-44 inch tires will measure about 2 inches smaller when mounted on a 10" wheel. Although it sounds backward, when you mount the 40" and up tires onto a 12" or 14" wheel.......they will get bigger. Most people think that stretching these tire onto wider wheels will shorten them. Actually the 10" wheels are squeezing them. When they are opened-up on bigger wheels, they will grow.....sometimes as much as the 2" that they were short in the first place. When you go this route, you will have more off-set. You cannot get a wheel that wide centered on the hub surface, they would hit the steering gear and would shorten your turning radius because they hit the springs while turning if you could make them fit. So you have effectively gained two problems at the same time..........larger diameter and more off-set. If you use wider wheels you will have to have more clearance/lift, especially if you off-road your truck.