Are you considering upgrading but aren’t sure if the wheels you like will meet your truck’s requirements? This is one of the most common problems facing all of the aftermarket wheel shoppers. To meet requirements, it is important to take certain factors into account including correct wheel and tire fitment, bolt patterns, wheel size, backspacing and offset. You may know the size of the wheel you require, but you may need to read an article to learn about bolt patterns. Also, what is backspacing and offset? Is there a difference between these two elements?
Backspacing and offset are two similar methods for measuring how a wheel can mount on a truck, but both are crucial for ideal wheel fitment. While backspacing and offset typically measure the same thing, they are also quite different. Backspacing measures the distance between the inside edge of a wheel and its mounting face, whereas offset measures the distance from the mounting surface to the wheel center. This is why the difference is so significant.
What Does The Wheel Offset Measure?
The wheel offset measures the distance from the mounting surface to the center of a wheel using millimeters. If you require a refresher course on the anatomy of the wheel, why not review our guide to wheel anatomy? The wheel offset can be negative in measurement, positive in measurement or zero in measurement.
A positive wheel offset refers to the mounting surface being on the front side of the wheel’s centerline. If there is a negative wheel offset, the mounting surface can be found facing the backside of the wheel’s centerline. However, if the wheel offset measures zero, this means that the mounting surface is placed at the centerline. It is essential that the offset is correct for proper fit and appearance. It is a key factor if you wish to lift the truck and install bigger wheels and tires.
If the offset measures higher, or you increase the offset from OEM, the mounting surface of the wheel will appear further inward on the truck. This is beneficial because it offers more clearance from the fender and tire’s the outside edge. However, it can also be detrimental because it reduces the space between the suspension and inner edge of the tire. This is not useful if you are attempting to upsize the tires and wheels for off-roading.
When the offset decreases or you choose to reduce the offset measurement from OEM, the wheel will have a mounting surface that is further outward on the truck. This enhances the space between the tire’s inside edge and suspension. The reduced offset is beneficial because it provides the truck with a wider stance; thereby, offering a greater lift for the truck. To gain more clearance from the suspension, you will need less offset. Some individuals choose to use a negative or zero offset measurement to push the tire and wheel to the outside and achieve the desired clearance.
What Does Backspacing Measure?
Backspace on the wheel measures the distance from the inside edge to the mounting face of the wheel. As the backspacing is decreased, you gain more inner wheel clearance. This means that reduced backspacing will lead to a smaller amount of the wheel in the wheel well. Moreover, as the amount of wheel in the wheel well is reduced, you lessen the risk of the wheel rubbing against suspension or brakes.
If the backspace is increased, you will lessen the amount of inner wheel clearance. If backspacing is increased, more wheel is placed in the wheel well. If this happens, there is a greater risk of the wheel rubbing against the suspension, brakes or the aftermarket mud flaps. This is highly detrimental!
If you need to lift the truck, it is important to take backspacing into account. In this case, it is vital that you pay close attention to the maximum backspace allowed according to the manufacturer of the truck’s lift kit. When upsizing the wheels, it is recommended that you do not choose a wheel with too much backspace or the wheel will not fit. If you do not upsize the wheel during the lift, it is advised you maintain the lift specifications. Always be aware of the maximum allowed backspace for the truck lift kit.
Backspace is typically expressed using inches and calculated using the following calculations:
The wheel width / 2 + the offset + half an inch.
If you wish to upsize the truck wheels for off-roading purposes, it is important to keep the following items in mind when considering backspacing and offsets:
If you continue to use the same wheel width, maintain the new offset within 5 mm of your last offset measurement in both directions.
If you opt for wider wheels or tires, it is recommended the backspacing is reduced.
Try to avoid any positive offset when choosing wheels for off-roading because too much offset can be dangerous.
Any oversized brakes or suspension can be detrimental to the amount of space in the wheel well. When choosing to oversize anything behind the wheel, it is recommended that you decrease the offset and backspacing measurements. If the calipers and upsized rotors protrude more than 3 inches into the wheel well, the inches must originate from the tire and wheel.