Wheel offset refers to the distance of a wheel’s mounting surface to its centerline and is vitally important to the performance of every vehicle and tire life. Although it affects tire life, it isn’t something you need to be concerned with if you are buying tires. It is important to understand wheel offset if you are buying new wheels or plan to alter the suspension of your vehicle.
Basics of Wheel Offset
There are three different types of wheel offset: positive, negative, and zero.
Positive offset means the mounting surface will be closer to the outside of the wheel. A positive offset gives a flat appearance to a wheel.
Negative offset means the mounting surface will be closer to the inside of the wheel, or deeper inside the wheel. As a negative offset increases the space between the outer edge of the wheel and the mounting surface, it offers more opportunity for decorative design such as dramatic angles, deep spokes or layering.
Zero offset means the mounting surface sits on the wheel’s centerline.
You might also see the terms high and low offset. These can both be applied to describe either positive or negative offset. High and low offset describe the degree of offset, or ‘how much’ positive or negative offset a wheel has. For example, a wheel could have a low negative offset, say -10 mm, or a high negative offset like -38mm. (Wheel offset is always measured in millimeters.)
The Relationship Between Wheel Offset and Backspace
When discussing wheel offset, backspace often enters the conversation. Backspace refers to the distance from the inside edge of the wheel (the side of the wheel facing the car) to the hub mounting surface. This measurement is made in inches.
More backspace means more wheel sits in the wheel well. With less backspace, less wheel sits in the wheel well and there’s more clearance between the wheel and the suspension.
So, how does backspace relate to wheel offset?
Simply stated, a positive offset wheel creates more backspace. The mounting surface of a positive offset wheel means more wheel sits behind the mounting surface. Negative offset, then, creates less backspace.
Why is Wheel Offset Important?
The position of a wheel has a big impact on the performance of your vehicle. Manufacturers ship vehicles with wheels designed specifically to optimize performance. Even the smallest shift in offset can impact vehicle performance.
A change in offset affects handling by changing the position of the tire while driving. Likewise, a change in wheel size without a change to wheel offset will have the wheel and tire out of position. For a positive offset wheel, this increases the chance of rubbing on the suspension. For a negative offset, the wheel might protrude and rub against the wheel well or even beyond the wheel well, which is not legal in some states.
A situation that creates rubbing on the suspension will wear out the wheel, tire, and suspension and strain the engine. Contact, or even minimal friction, with the wheel well will destroy the tire and have a similar effect on the suspension and engine. Fortunately, there are plenty of resources to help ensure you get the right wheels for your vehicle.
Why You Don’t Need to Stress Wheel Offset
If you need to replace your wheels for daily use, you can measure your current wheel, contact the manufacturer, or just talk with the tire and wheel professional where you plan to buy the wheels.
If you plan to upgrade your vehicle’s look, getting the right tire offset is important, but not difficult. Do you plan to lift your suspension? Most kit manufacturers include details that explain the offset and backspace needed based on your vehicle. It’s important to get the wheel size combination matched properly with your vehicle, but there are plenty of resources available. The kit manufacturer, vehicle manufacturer, or a wheel and tire installer through tireamerica can help fit the best wheel offset to guarantee your vehicle’s performance.