Enter the tire size, transmission ratio, spur, and pinion into the calculator to determine the rollout.

Rollout Formula

The following formula is used to calculate rollout:

RO = D*PI*P / (S * IR) 
  • Where RO is the rollout
  • D is the diameter of the tire
  • P is the pinion
  • S is the spur
  • IR is the internal drive ratio (transmission ratio)

In this formula, the rollout will have the same units as the diameter. So, if tire diameter is entered as inches, the rollout will be in inches.

To calculate rollout, multiply the circumference by the pinion, then divide by the product of the spur times the drive ratio.

What is a rollout?


A rollout is defined as the total distance traveled by a vehicle per 1 revolution of an engine.

How to calculate rollout?

Example Problem:

The following example outlines how to calculate a rollout.

First, determine the diameter of the tire. In this example, the diameter is 20 inches.

Next, determine the spur. In this case, the spur is .75.

Next, determine the pinion. This is found to be 1.65.

Next, determine the internal drive ratio. In this example, this is calculated to be 1:4 = .25.

Finally, calculate the rollout using the formula above:

RO = D*PI*P / (S * IR)

RO = 20*3.14159*1.65 / (.75 * .25)

RO = 552.91