The offset of a wheel is the distance from the hub mounting surface to the wheel's center line. The wheel offset is measured in millimeters and results in positive, negative, or zero offsets. A positive offset is when the hub mounting surface is toward the front or side of the wheel.
The mounting portion of the wheel on the vehicle is aligned with the center of the wheel.
The offset is positive when the wheel's core is in the front portion of the wheel, in half on the roadside. This causes most of the wheel to be toward the brakes and suspension components. Positive offsets are generally found on front-wheel drive cars.
Unlike positive offset, a negative offset will bring the mounting area into half behind the wheel's centerline, leaving more room for the suspension components and brakes. These wheels, considered concave, are more common on tuner cars and trucks with a mounted suspension.
The proper offset on the right wheel
Not having the proper offset can directly affect the compatibility of a wheel on your vehicle. It can also have an undesirable impact on your ride, comfort, or even the mechanics of your vehicle. When changing wheel specifications, such as width, it is essential to adjust the offset so that the wheels do not stick out too far from the fenders (commonly referred to as aggressive wheels) and have enough clearance to not interfere with the brakes or suspension.
How to measure the wheel offset?
- Measure the overall width of the wheel in millimetres
- Divide the result of step #1 by 2
- Put the wheel flat (face up)
- Measure the base in millimetres where is supported the wheel up to the vehicle contact surface
- Take the result of step #2 and subtract the result of step #4
The more you increase the offset, the more the rim will be inside the body. If the offset is too important, the rim may rub against the brake calipers or the shock absorber.
The more the offset is reduced, the more the rim will be out of the body. If the offset is too small, the rim may rub against the body of the outer wheel arch, especially when turning the front wheels.