Despite what the news tells us the world is not all doom and gloom. If you stop watching the news, get outside, and go wheeling the world is a better place. It seems there a lot of people who feel that way and our hobby continues to grow. With new folks joining it’s important to cover things like picking the right wheel so the experience is a good one and they stay enthusiasts for a long time.
Wheel Offset and Backspacing Explained
We often get questions submitted to the site and one of the more recent questions was about wheel backspacing and offset. The author was trying to buy aftermarket wheels that would fit their Jeep after installing a new lift. The lift manufacturer recommended a wheel with 3.75 to 4.5 inches of backspacing and a maximum width of 9 inches to clear all of the suspension and give better control. Before we talk about why that is let’s go over what that is.
As you can see in the image above backspace is the distance from the mounting surface to the rear edge of the rim. The smaller this number the less rim material is wrapped around the brakes and suspension. The smaller the number the “deeper” the wheel is (The right side is an example of this). Those big wheels that have the lugs and centers sunk in have a very small backspace dimension
Wheel offset is where the mounting surface is located in relation to the wheel center line. It adds a somewhat confusing dimension to selecting wheels. We mention it because there are some manufacturers who will notate their measurements using a formula like 17×7 with a 3.5 inch backspace or 0MM offset. Which in simplest terms means the mounting surface is right in the middle. A 17×8 with a 3.5 inch backspace would have a -25MM offset. It’s also a bit of Metric versus Imperial measurements.
Understanding Bolt Patterns and Their Importance
A stock Jeep comes with 17×8 inch wheels, 6 inches of backspace, and a 5 x 5 lug pattern. Lug nut pattern and dimensions are important in any discussion about wheels. You can get the backspace correct, the offset correct, choose your perfect rim in the ideal size and not be able to use it. Why? It won’t bolt on to your wheel studs. The Jeep 5×5 means 5 lugs, 5 inches apart. Older Jeeps used a 5×4.5 which means, you guessed it, 5 lugs 4.5 inches apart. If you don’t know your lug nut pattern just check your manual or owners forum. Another factor is hub diameter. That’s the center hole in the wheel that fits over a ridge on the wheel hub. Some wheels are hub centric to carry the vehicles weight and the lugs are responsible for forward movement. Some vehicles are lug centric where the lug nuts do both.
Wheel Width and Diameter: Key Factors in Wheel Fitment
Wheel width can determine tire shape, does it balloon in the middle, is it stretched. How the tire wears, and whether your tire fits in the wheel well of your vehicle. Too wide and you run out of room, too narrow and the tire bulges and wears in the middle quickly. Same thing goes for wheel diameter. Too small and it might not fit over your brakes, too large and it won’t fit in your wheel well.
That’s the basics. There are other items we can cover like spacers, lug pattern conversion, lug centric versus hub centric, wheel design and more. Send us an email or comment below if you want more.
