Enter the rotations per minute (RPM) of the axle and the wheel diameter into the calculator to determine the wheel speed.

## Wheel Speed Formula

The following formula is used to calculate a wheel speed.

S = [2*PI*(D/2)] / [ RPM/60 ]

- Where S is the wheel speed
- RPM is the rotations per minute
- D is the diameter

## Wheel Speed Definition

**What is wheel speed? **Wheel speed commonly refers to the instantaneous tangential velocity of a wheel at a specific diameter that is rotating at a constant RPM.

## Example Problem

How to calculate wheel speed?

**First, determine the RPM.**Measure the total rotations per minute the wheel turns at. For this example, the RPM is found to be 100.

**Next, determine the diameter.**Measure the full diameter of the wheel or tire. For this problem, the diameter is found to be 20inches.

**Finally, calculate the wheel speed.**Using the formula above, we find the wheel speed to be: S = (2*PI*(20/2))/(100/60) = 37.699 inches per second. The time units for this equation should always be seconds, while the length units will be whatever the diameter is measured in.

## FAQ

**Does wheel size affect speed? **Wheel size will change the speed of a vehicle if the RPM of the wheel stays constant. Increasing the wheel size will increase the speed when RPM is constant, and decreasing the wheel size will decrease the speed when RPM is constant. In the real world, keeping a constant RPM with a larger wheel requires more torque.