>>> How to Measure Wheel Offset <<<

[Tork Monster]

The question of wheel offset is often brought up here, so I thought I would post this when I measured the offset of my new wheels.

Wheel offset is the difference between the center of the wheel and the mounting surface. Positive offset is when the mounting surface is closer to the outside of the wheel; negative offset is when the mounting surface is closer to the inside of the wheel. Negative offset will push the wheel outwards.
Most wheels have a positive offset to allow more room for the brakes and suspension parts. Negative offset wheels are put on Hondas to make the car look funny.

To measure the offset:
1)- place the wheel flat on the floor and place a straightedge across the wheel. This will work for wheels mounted with tires too.

2)- measure the overall width of the wheel/tire (from the underside of the straightedge to the floor):



3)- measure the distance to the mounting face of the wheel.



4)- Divide the overall width of the wheel/tire by two to find the center of the wheel. Subtract the distance measured to the mounting surface by the distance to the center of the wheel. This difference is the wheel offset.

For my wheels (GSM Intro Forged 22" x 10.5") the overall (with tires) measured 10.88". The distance to the mounting face measured 6.13".
The offset is [6.13" - (10.88"/2)] = 0.69"
Multiply inches by 25.4mm/inch to convert to millimeters
0.69" x 25.4mm/inch = 17.5mm

Considering the floor in my garage was poured before automatic transmissions were invented, I would estimate the offset is between 15 and 20mm.