Wheel Offset & Backspace - Questions & Answers

PerformanceLifts.com receives 1000's of e-mails each year and a good percentage of those involve questions about selecting the correct size wheel for use on a leveled or lifted vehicle. Wheel offset and backspace are critical to ensure your tire and wheel combo fit your Truck or SUV correctly. A wheel with too much backspace may not even bolt up to the vehicle, a wheel with too little backspace may allow the tire to rub when turning. We've already put together a growing list of factory wheel sizes and the offset / backspace (available by clicking here) but customers have asked for more information. This instructional page is designed to explain how offset and backspace are related and how they can affect tire and wheel fitment on your vehicle.

Question: Will the aftermarket wheels I am looking at purchasing stick out farther than my factory wheels?

Answer: This question is best answered using an example. If your factory wheel is 8.00" inches wide and you install an aftermarket wheel that is 9.00" inches wide the width increase alone will push the outer wheel lip out by 1.00". In other words, the 9.00" wide wheel will stick OUT by an additional inch. Here is where Offset and Backspace become really important. If your factory 8.00" wide wheel has +25.4 (positive 25.4 millimeters) of offset it will have a backspace measurement of 5.50" inches. If aftermarket 9.00" wide wheel has -12mm (negative 12 millimeters) of offset the backspace measurement will be reduced to 4.53" inches. That means the change in offset has resulted in a change in backspace. More specifically the reduction in offset has resulted in a reduction of back space. That means the -12mm offset will push the aftermarket wheel OUT an additional 1.00" inch more than the factory wheel, which results in a total outer wheel lip width increase of 2.00" inches. The amount the wheel sticks OUT beyond the fenders will go up if you run an aftermarket wheel that is wider than your factory wheel. The wheel will stick OUT even more if the amount of offset or back space is reduced.

Question: Will a (insert tire size here) fit with my lift? The lift /leveling kit manufacturer says it will!

Answer: That depends largely on the width and back space of your wheels. Lift kit and leveling kit manufacturers will usually also recommend the wheel size for use with the maximum recommended tire size that will work with their lift. If a manufacturer says "Clears 35" Tires on 8" Wide Wheel w/5.00" Backspace" that means you need to follow those recommendations. Let's say that instead of running the recommended 8.00" wide wheel you decide to install an aftermarket wheel that is 12.00" inches wide. That means the new wheel will stick OUT approximately 4.00" inches more than the recommended wheel. A combination like that (35" tire on a 12" wide wheel) will in almost all cases cause clearance issues because when the tire and wheel go beyond the fender opening the tire is more likely to rub when turning. A general rule of thumb is if you want to run a WIDE wheel you will need to run a SHORTER diameter tire to ensure proper clearance when turning.

Question: Why does the Lift / Leveling Kit manufacturer say I can't use my factory wheels with their lift? They are the same diameter and width as the recommended aftermarket wheels!

Answer: Simply put, BACKSPACE! If a manufacturer states their product is not compatible with the factory wheel you need to pay attention to this information. The number one reason is because the factory wheel will rub the aftermarket suspension components. Some lift and leveling kits will replace factory steering and suspension components with ones that reduce the amount of clearance between the wheel and tire sidewall. A factory 17x8 wheel with 5.50" inches of back space may rub the suspension components, but an aftermarket 17x8 wheel with 4.50" inches of back space will not. In most cases the lift and leveling kit manufacturers will specify if their product is compatible with a specific factory wheels. For instance, with certain lifts a factory 20" diameter wheel can be safely used when a factory 17" wheel cannot. The reason for this is the opening of the 20" wheel allows for clearance with the suspension components that the 17" wheel does not.

Question: I've found an aftermarket wheel I really like, but it's available in two different offset options. Which should I use?

Answer: A number of wheel manufacturers will offer the same wheel style in different offsets. We recommend selecting the offset that best matches the recommendation provided by the lift or leveling kit manufacturer. Remember, as positive offset increases so does back space. You might find that one wheel offset will work just fine and the other is not at all compatible.

Question: My buddy / Internet says I can run this size tire just fine, even though the manufacturer says I can't. What should I do.

Answer: Will your buddy / Internet fix things if the tire and wheel combination you select doesn't work out right? If you spend $5000.00 on a bitchin' custom 22x12 wheel and tire setup that doesn't fit properly is your buddy going to fix that for you? We know the Internet won't. If you want to be sure the tire and wheel combination will fit we recommend you follow the lift or leveling kit manufacturers recommendations. If you still have questions please click on the ASK A QUESTION link located at the very top of this page.