What Is Wheel Offset? Measurement, ET, and Fitment

The offset of a wheel is the distance (in millimeters) from the hub mounting surface to the wheel’s true centerline. Getting offset right keeps brakes, suspension, and fenders happy—and delivers the stance you want without rubbing. Below we explain offset types, how to measure it, and how to choose a safe value for your vehicle.

Offset Basics (ET)

• Positive Offset (+ET): Hub pad sits toward the outside face of the wheel; pulls the wheel inward under the fender. Common on modern cars and many SUVs.
• Zero Offset (ET0): Hub pad aligns with the wheel’s centerline.
• Negative Offset (?ET): Hub pad sits toward the inside barrel; pushes the wheel outward for a deep-lip look. Common on some trucks/off-road builds.

Most wheels are stamped “ET” plus a number (e.g., ET35 = +35 mm). Offset works together with backspacing, wheel width, and tire size to determine inner/outer clearance.

Measurements: How to Measure or Calculate Offset

You can measure directly or calculate from backspacing and width:

1. Measure Overall Width: Actual wheel width is about 1" greater than the labeled width (lip-to-lip). A 8.5" wheel measures ~9.5" overall.
2. Find the Centerline: Overall width ÷ 2.
3. Measure Backspacing: With the wheel face down, place a straightedge across the back rim lip and measure down to the hub pad.
4. Calculate Offset: Offset (in) = Backspacing ? (Overall Width ÷ 2). Then convert: Offset (mm) = Offset (in) × 25.4.

Quick guide: Offset (mm) ? (Backspacing ? (Rim Width + 1)÷2) × 25.4. Use our Backspacing Calculator and Wheel & Tire Size Calculator to verify results.

Clearance Checks

• Inside clearance: Positive offset moves the wheel inward toward struts, control arms, and inner fenders. Verify with the Wheel Visualizer and tape measurements.
• Outside clearance: Lower (or negative) offset moves the wheel outward toward fender lips and flares; consider alignment and suspension travel.
• Brake calipers: Spoke design matters. Even with correct offset, some styles require more caliper envelope. Check the specific model’s brake clearance.
• Width changes: Each 1" wider wheel adds ~12.7 mm per side total (6.35 mm per side). To keep similar inner clearance, reduce offset roughly by that 6.35 mm per added inch of width.

For deeper detail, see Car & Truck Wheel Offset Explained and compare related specs like bolt pattern and hub bore.

Safety & Load Ratings

• Component stress: Extreme offset can increase bearing load, alter scrub radius, and affect steering feel. Closer to OE spec is typically safest for street use.
• Load matters: Offset does not change a wheel’s load rating—choose wheels that meet or exceed your vehicle needs. See Wheel Construction Types and Proper Care of Your Wheels.
• Tire fitment: Validate section width and shoulder shape using the Tire Size Comparison Calculator and Plus/Minus Sizing Calculator.

Professional Fitment Advice

Tell us your vehicle and goals (flush fit, brake upgrade clearance, off-road stance), and we’ll dial in width, offset, and tire size. Browse Custom Wheels or shop by style in Shop Wheels; then pair tires for a complete package.

Get Help

• Build-and-check your setup with our Wheel Visualizer and calculators above.
• Prefer bolt-on convenience? See our Wheel & Tire Packages.
• Contact Us for one-on-one help from a Performance Plus Tire fitment specialist.

Reviewed by the Performance Plus Tire Fitment Team.