Wheel Offset Calculator

Wheel offset determines how far your wheel sits inward or outward from the hub, which affects handling, clearance, and whether your tires rub against the fender or suspension. Enter your wheel width, offset (ET), tire width, tire profile, and wheel diameter into the Wheel Offset Calculator to get your calculated backspace, frontspace, calculated offset, sidewall height, and total diameter. You can also enter a known backspace value to calculate the corresponding offset in mm.

inches

Width of the wheel rim

mm

Distance from centerline to mounting surface

inches

Distance from mounting surface to back edge

mm

Width of the tire in millimeters

%

Sidewall height as percentage of width

inches

Diameter of the wheel

Results

Calculated Backspace

--

Calculated Offset

--

Total Diameter

--

Sidewall Height

--

Frontspace

--

More Automotive Tools

Frequently Asked Questions

What is wheel offset?

Wheel offset is the distance in millimeters from the centerline of the wheel to the mounting surface. Positive offset means the mounting surface is toward the front (outside) of the wheel, while negative offset means it's toward the back (inside).

What is wheel backspacing?

Backspacing is the distance from the mounting surface to the back edge of the wheel rim, measured in inches. It determines how far the wheel sits inward toward the suspension and brake components.

How do I convert between offset and backspacing?

To convert: Backspace = (Wheel Width ÷ 2) + (Offset ÷ 25.4). To find offset from backspacing: Offset = (Backspace - Wheel Width ÷ 2) × 25.4. The conversion accounts for the difference between inches and millimeters.

What happens if I change my wheel offset?

Changing offset affects wheel positioning relative to the fender and suspension. More positive offset moves the wheel inward (less poke), while more negative offset moves it outward (more poke). This impacts clearance, handling, and appearance.

Can I use wheels with different offset than stock?

Yes, but within reasonable limits. Small changes (±10-15mm) are usually safe, but larger changes may require modifications or cause clearance issues. Always check for adequate clearance from suspension, brakes, and fenders.

What is the difference between frontspace and backspace?

Backspace is the distance from the mounting surface to the back edge of the rim. Frontspace is the distance from the mounting surface to the front edge. Together, they equal the total wheel width plus rim thickness.

How does tire size affect overall wheel fitment?

Tire width and sidewall height affect the total wheel package size. Wider tires may require more clearance, while lower profile tires reduce overall diameter. The calculator helps determine the complete wheel and tire dimensions.

Why is wheel offset important for vehicle safety?

Proper offset ensures adequate clearance from suspension components, brake calipers, and fenders. Incorrect offset can cause tire rub, affect steering geometry, put extra stress on bearings, and create safety hazards.