Wheel Offset and Backspacing Explained for Leveled and Lifted Trucks

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Offset and backspacing both describe where a wheel sits relative to the truck. Offset is measured in millimeters and backspacing in inches, and either one tells you how far the wheel will stick in toward the suspension or out toward the fender. Getting them right is the difference between a wheel that clears everything and one that rubs.

What offset means

Offset is the distance from the wheel’s mounting surface to the centerline of the wheel, measured in millimeters.

• Positive offset: the mounting surface is toward the outside (street side) of the wheel. The wheel tucks further under the fender. Most factory wheels have a positive offset.
• Zero offset: the mounting surface is exactly at the centerline.
• Negative offset: the mounting surface is toward the inside of the wheel, so the wheel and tire sit further out. Many aftermarket truck wheels use a negative offset such as -12 or -24.

What backspacing means

Backspacing is the distance, in inches, from the wheel’s mounting surface to its back edge. A larger backspacing number pulls the wheel closer to the suspension; a smaller number pushes it out. The two measurements are linked: backspacing in inches equals half the wheel width plus the offset in millimeters divided by 25.4.

For example, a 9-inch-wide wheel with a 0 mm offset has about 4.5 inches of backspacing. The same wheel at -24 mm offset has about 3.6 inches, meaning it sits roughly an inch further out.

Why it matters on leveled and lifted trucks

A leveling kit or a lift changes where the tire travels. A wider or more negative-offset wheel moves the tire outward, which brings the tire closer to the fender lip, and a larger tire may rub when the suspension compresses or the wheel is turned. Moving the wheel inward brings the tire closer to the control arms, frame and brake components.

• Check clearance to the fender, bumper and mud flaps at full steering lock.
• Check inner clearance to the control arm, sway bar and brake lines.
• Check that the brake caliper clears the inside barrel of the wheel.

Changing offset affects the truck

Pushing the wheels outward increases the scrub radius and puts more leverage on the wheel bearings and steering parts. Small changes from the original offset are usually fine; large changes can wear parts faster and change steering feel. Many people stay within a modest range of the factory offset when the truck is used for towing or daily driving.

Use the numbers when you shop

How to measure what you have now

Take one wheel off the truck and lay it face down on a flat surface. Measure the overall width of the wheel from lip to lip, which is the wheel width. Then lay a straightedge across the back of the wheel and measure from it down to the mounting surface. That is your backspacing. Use the relationship above to turn it into offset, or look for the offset stamped on the back of the wheel, often written ET followed by a number in millimeters.

Reading offsets in a listing

Offsets are written as a number with a plus or minus, such as +18 or -12. A higher plus number tucks the wheel in more. A larger negative number pushes it out. When two wheels are the same width, the one with the more negative offset will stick out further, and the difference in millimeters divided by 25.4 gives the difference in inches.

What a leveling kit changes

Many pickups sit slightly lower at the front than at the rear. A leveling kit raises the front so the truck sits level, which also opens up room for a taller tire. It does not change the width available at the fender, so a wider wheel or lower offset still needs checking for rub at full steering lock.

Spacers and adapters

Wheel spacers push a wheel outward without buying a new wheel. They add another joint to the wheel mounting, and quality varies a lot. Hub-centric spacers that bolt on with their own studs are the safer style. For a truck that tows or hauls, many owners prefer to buy a wheel with the right offset rather than add a spacer.

If the tire rubs

• Check which part rubs and at what point: full lock, full compression or both.
• A narrower tire, a different offset or a leveling or lift kit are the usual fixes.
• Some owners trim fender liners or roll fender lips. Check your local rules on fender coverage before the tire sticks out past the body.

Write down your factory wheel width and offset, then compare any new wheel’s width and offset against them. A wheel one inch wider with the same offset sits about half an inch further out on each side. When you are ready, browse our 8-lug truck wheels and check the offset listed for each one. Our 8-lug wheel guide covers the bolt patterns, and the fitment checklist lists the other checks to make before you order.