Free tool
Wheel offset calculator
Compare your current wheels with a new set and see exactly how far they'll poke out or tuck in, the change in backspacing and track width, and whether they're likely to rub — before you buy.
8.00" +18 mm → 8.50" +0 mm
Big change — likely to rub without trimming or a lift
| Spec | Current | New | Change |
|---|---|---|---|
| Wheel width | 8.00" | 8.50" | +0.50" |
| Offset (ET) | +18 mm | +0 mm | −18 mm |
| Backspacing | 5.21" | 4.75" | −0.46" |
| Outer edge from hub | +96 mm | +121 mm | +24 mm |
| Inner edge from hub | +132 mm | +121 mm | −12 mm |
What this means for your truck
- Sticks out about 24 mm further per side — more aggressive stance, but watch fender/flare clearance, tire spray and scrub at full steering lock.
- Inner edge moves about 12 mm away from the suspension — more inner clearance to play with.
- The lower offset pushes the wheel out the same as a 18 mm wheel spacer would.
- 0.5" wider — a wider wheel grows toward both the fender and the suspension equally unless the offset changes too.
Geometry only — real clearance also depends on tire size, suspension, brakes and how square your hubs run. Always test-fit and check at full steering lock and full compression before buying tires.
Offset, backspacing & poke — explained
Three ways of describing where the wheel sits on the hub. Once you see them together, fitment stops being a mystery.
Positive offset
Mounting face toward the street side; the wheel tucks in. Standard on most modern trucks.
Zero offset
Mounting face sits right on the wheel's centerline — a neutral, balanced stance.
Negative offset
Mounting face moves inboard; the wheel pushes out for poke or a deep-dish look.
Backspacing
Inches from the mounting face to the inner lip — the number that governs inner clearance.
Wheel offset — frequently asked
What is wheel offset (ET)?
Offset is how far the wheel's hub mounting surface sits from the true centerline of the wheel, measured in millimetres and often stamped as "ET". Positive offset means the mounting face is toward the street side, tucking the wheel inward (common on modern trucks). Zero offset puts the face on the centerline. Negative offset moves the face inward, pushing the wheel outward for that "poke" or deep-dish look.
What is the difference between offset and backspacing?
They describe the same thing from different reference points. Offset is measured in millimetres from the wheel centerline. Backspacing is measured in inches from the mounting face to the inner lip of the wheel. Backspacing = (wheel width + 1) ÷ 2 + offset in inches, so a lower (or negative) offset gives less backspacing and more poke. This calculator shows both for each setup.
Will a lower offset make my wheels stick out and rub?
A lower or negative offset pushes the wheel outward (more poke), which widens your track and can rub the fender or flares at full steering lock or full suspension compression. A higher offset or wider wheel can instead push the inner edge toward the suspension and brakes. This tool shows exactly how many millimetres each edge moves so you can judge the risk.
Is changing offset the same as running wheel spacers?
Almost — a wheel spacer of a given thickness reduces effective offset by that amount and pushes the wheel out by it. So dropping offset by 18 mm gives the same outward stance as an 18 mm spacer. The difference is that a spacer keeps your current wheels and adds a part to maintain and torque, while a new offset is built into the wheel.
What offset should I run on my truck?
There is no single right answer — it depends on your wheel width, tire size, suspension and how much poke you want. As a starting point, staying within a few millimetres of your factory offset is the safe, no-rub choice. If you go more aggressive, always test-fit and check clearance at full lock and full compression before buying tires.
Does a wider wheel change where the tire sits?
Yes. At the same offset, a wider wheel grows toward both the fender and the suspension equally (half the extra width each way). That is why wider wheels are often paired with a different offset — to keep the tire clear of one side or the other.
