Measuring Rim Width
The rim width (also referred to as wheel width) plays a key role when replacing rims or modifying your tire size. The rim width and tire size must be compatible in order for the tire and rim assembly to maintain the safety and handling requirements of the vehicle. The rim width is measured from rim flange to rim flange. The rim flange is the mounting surface that the tire sits on when mounted to the rim, as seen in the image above.
Rim Width and Tire Size
It's very important to stay within the range of approved rim width/tire size combinations. The tire size determines the range of rim widths that are safe to use.
For example, a tire size 245/45R-20 has a rim width range of 7.5" to 9.5". This means that this tire size would fit a rim size of:
- 20 X 7.5
- 20 X 8
- 20 X 8.5
- 20 X 9
- 20 X 9.5
Although it may be possible to mount a tire to a rim width that is not recommended, doing so can lead to tire failure, irregular tire wear, or poor vehicle performance and handling. Discount Tire Direct will only mount a tire on a recommended rim width.
Rim Width and Performance
The width of your rim has an effect on how your vehicle performs. For example, if you were to increase the width of your original equipment rim without changing the original equipment tire size, there is less flexibility in the tire sidewall, which allows for faster steering response. However, with a stiffer sidewall, the tires ability to absorb impacts and road turbulence is transferred to the vehicle and is felt by passengers. If you were to decrease the width of your rim without changing the overall tire size, there is more flexibility in the tire's sidewall, which allows the tire to absorb impacts and provides for a smoother ride.