Wheel Offset and Backspacing Explained

Offset is the distance in millimeters between the wheel’s mounting surface (where it bolts to the hub) and the centerline of the wheel.

• Positive offset (for example +25 mm): the mounting surface is toward the outside. The wheel sits further in, closer to the suspension.
• Zero offset: the mounting surface is exactly at the centerline.
• Negative offset (for example −12 or −44 mm): the mounting surface is toward the inside. The wheel sticks out further for a wider, more aggressive stance.

Backspacing is the distance in inches from the mounting surface to the inner edge of the wheel. More backspacing means the wheel sits further inward.

A common estimate to convert offset to backspacing is: backspacing (in) ≈ wheel width ÷ 2 + 0.5 + offset (mm) ÷ 25.4.

Example: a 9-inch-wide wheel with a −12 mm offset has about 9 ÷ 2 + 0.5 − 0.47 ≈ 4.5 inches of backspacing.

• Less backspacing moves the tire away from the upper control arm and inner suspension, which can help bigger tires clear.
• It also moves the tire closer to the fender edge, which can cause rubbing when turning or flexing, and may put the tire outside the fender.
• Very aggressive offsets increase leverage on wheel bearings and steering components and can make the truck more sensitive to ruts.
• Some states require tires to be covered by the fender. Check local rules before running a wide stance.

• Bolt pattern: the number of lugs and the circle they sit on, such as 6x135 or 6x139.7.
• Center bore: the hole must fit your hub, either exactly (hub-centric) or with a hub-centric ring.
• Lug nut seat and thread size: aftermarket wheels often need different lug nuts.
• Load rating: the wheel must be rated for your truck’s weight.