One of the first pickup-truck modifications made by many customers is the replacement of stock rims with a more stylish set of aftermarket wheels. Aftermarket wheels set your truck apart from similar models on the road, perhaps more than any other accessory. There are several measurements that need to be taken into account when purchasing aftermarket wheels in order to ensure proper fitment. In this guide, we’ll examine those measurements in addition to reviewing available finishes and the two primary means of building a wheel.
A cross-section of a wheel
Offset is the position of a wheel’s mounting plate relative to the centerline of the wheel. A wheel with its mounting plate pushed away from the vehicle or “street side” is said to have a positive offset, while a wheel with its plate pushed towards the vehicle or “brake side” has a negative offset. It’s also common for a mounting plate to be located in the exact center of the wheel, a design referred to as zero offset. The measurement is usually expressed in millimeters. Oftentimes, customers will request a wheel with a large negative offset since it creates a striking deep-dish look on the rim. However, it’s important to take note of the impact that offset has on a wheel’s backspacing.
The distance from a wheel’s mounting plate to its rear edge is referred to as backspacing. Measured in inches, backspacing is one of the most important measurements to take into account when choosing a wheel; this is because original equipment manufacturers set backspacing requirements to make sure the wheel doesn’t hit your brake calipers or any suspension components. Keep in mind that if you install a suspension lift kit, your backspacing requirement may change. In such cases, refer to the lift kit manufacturer’s installation instructions for the correct backspacing measurement.
Your vehicle’s bolt pattern is determined by the number of bolts used to secure the wheel to the hub, and the diameter of the bolt-mount circle. This measurement can be expressed in either inches or millimeters. For example, a wheel with six mounting bolts mounted on a 5.5-inch circle would have a bolt pattern of 6x5.5 inches or 6x139.7mm.
The diameter of a wheel is measured from just below the outer rim. Expressed in inches, the diameter is the first dimension referenced in wheel sizes. Large wheels of 22 inches and above frequently feature large widths and high negative offsets, making them popular for the most extreme customized trucks.
The width of a wheel is the measurement of the space between the inner and outer rims. This measurement is taken in inches and is the second dimension referenced in a wheel size. Therefore, a wheel that is labeled as 20x10 will be twenty inches in diameter and ten inches in width.
Also referred to as the hub hole, the center bore is the hole in the center of the rim. The diameter of this hole is an important measurement to keep in mind when shopping for wheels since it must at least be the same size as your OE center bore or larger.
Sometimes called wheel-load rating, the load capacity of a wheel is the weight of the heaviest axle it is designed to support divided by two. For instance, if a pair of wheels is capable of supporting a gross axle weight (GAW) of 4000 lbs, it will be marked with a load rating of 2000 lbs. Exceeding a wheel’s load capacity can have dangerous results.
Aftermarket wheels are available in a wide array of colors including black, chrome, and even custom-painted to match the color of your truck. To explore wheel finish options, check out our guide to truck wheel finishes
A satin black wheel
A chrome wheel
Two piece wheels are a common design among larger wheels
A cast wheel is created by pouring molten aluminum into a wheel-shaped mold. The cost-effective casting process produces a wheel of good quality and durability. For this reason, cast wheels are more common than forged wheels, both as aftermarket replacements and original equipment.
Forged wheels are created by milling a round bar of forged aluminum in a CNC machine. Less material is required to create wheels via the forging process, resulting in a lighter product than comparable cast wheels. Forged wheels are also stronger than their cast counterparts, which means forged wheels can be made in larger sizes that cast wheels can’t support. Forged wheels do tend to carry a higher price tag than cast wheels due to the expense of the forging process. However, they provide greater long-term value thanks to their superior structural integrity.
A one-piece wheel is made from one continuous piece of metal. This design represents the majority of wheels on the road today due to its affordability compared to two-piece wheels.
A two-piece wheel consists of a separately manufactured center section and rim bolted together. This is done in such a way to make the wheel appear seamless. Compared to the one piece design, two-piece wheels are easier to build in larger sizes with deep negative offsets.
Trucks with dual rear wheels (DRW) have very specific offset and backspacing requirements
Due to the specific offset and backspacing requirements of dually wheels, they deserve special mention as a wheel construction style all their own. If you’re shopping for a vehicle equipped with dual rear wheels, make sure that you choose wheels specifically designed for a dually set up.