Trailer wheels are measured by several key dimensions to ensure proper fit and functionality:
1. Bolt Pattern
- The bolt pattern, also known as the lug pattern, refers to the number of bolts or lugs on the wheel and the distance between their centers.
- To measure the bolt pattern, measure from the center of one bolt hole to the center of the opposite bolt hole.
- The measurement is typically written as "number of lugs x bolt circle diameter".
- For example, a 5 on 4.5 bolt pattern means there are five lugs arranged on a circle with a diameter of 4.5 inches.
2. Rim Diameter
- The rim diameter refers to the inner diameter of the wheel, where the tire bead seats.
- It is typically measured in inches, such as 15 inches or 16 inches.
3. Rim Width
- The rim width measures the distance between the bead seats on the rim.
- It is also measured in inches, such as 6 inches or 8 inches.
4. Offset
- Offset refers to the distance between the wheel's mounting surface and the center of the wheel.
- It is typically measured in millimeters and can be positive, negative, or zero.
5. Load Rating
- The load rating indicates the maximum weight a wheel can safely support.
- It is typically displayed on the wheel itself and is expressed in kilograms or pounds.
6. Tire Size
- The tire size is not strictly a wheel measurement but is closely related.
- It specifies the tire's width, aspect ratio, rim diameter, and load index, such as 205/75R15.
Understanding these measurements is crucial when replacing or upgrading trailer wheels to ensure compatibility and safety.
