Tire/Wheel Sizing Guide
TIRE/WHEEL SIZING GUIDE
Offset - Backspacing
The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types (measured in millimeters).* Wheel backspacing is the distance from the hub mounting surface to the inside wheel lip (back side of the wheel) and is usually measured in inches. When chosing wheels it is important to pay attention to the backspacing. A common "offset" for example is +12mm or -12mm. In this example a +12mm wheel would be a positive offset wheel and a -12mm wheel would be a negative offset wheel. In this case "0" is the centerline of the wheel which means a +12mm offset is a wheel with a hub mounting surface 12mm (roughly just over half and inch) further outwards toward the front of the wheel. Think front wheel drive car wheels for reference. A wheel with a -12mm offset would have a hub mounting surface 12mm inside of the wheel centerline, or closer to the back side of the wheel lip. This type of wheel usually has a "deep" look as compared to a zero or positive offset wheel.
Most all factory truck wheels are positive offset to one degree or another.
Installing a wheel with less rear of wheel backspacing than the factory wheel results in the wheel sticking out further than the stock wheel did.
The hub mounting surface is even with the centerline of the wheel.
The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.
If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We have test fitted thousands of different vehicles for proper fitment. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.
*Backspacing, similar to offset, is the distance from the hub mounting surface to the inside lip of the wheel (measured in inches).