How To Measure an ATV Tire

How To Measure an ATV Tire
by Jake Stone

A commonly asked question is "How do I measure the height of an ATV tire?"  Contrary to popular belief and the internet, an ATV/UTV tire’s height is not measured using a steel tape placed next to an upright tire, nor is done using an un-mounted tire, nor without the tire being aired to maximum operating psi.

The industry standard to calculate ATV tire height is by measuring the circumference and dividing by pi (3.14), and then rounding down or up accordingly to get a whole number.  In some cases a tire may be rounded to the nearest half inch and included in the size Example: 39.5x13.50-15

Follow these steps to properly measure your ATV tire:

1) Mount and inflate the tire to maximum operating pressure.  Generally speaking, this is usually 7 to 8 psi for most ATV tires.  However, for some larger tires, specifically those suited for UTV's or Side-by-Sides, they often have a higher maximum operating pressures and loads.  The tire height is often sized at this maximum operating pressure, which can be as high as 12-21 psi, depending on the tire.  The maximum operating pressure is indicated on the sidewall of the tire.  

2) The weight of the ATV or Side-by-Side should not be on the tire.  The tire should either be removed from the machine, or the machine should be jacked up so that the tire does not touch the ground, and the weight of the machine is completely off the tire. The weight of the machines can vary tremendously.  For utility ATV's this could be a light weight 250/300 or it could be a heavier 4 seater SXS.  The weight of the machine affects the amount of tire "squat", and can adversely affect the measurement of the tire.

3) Use a soft tape measure and measure the circumference of the tire at the centerline (highest point) of the tread.

The diameter will be equal to the circumference divided by pi (3.14).  This will give you the overall tire height in inches.

Example: If the circumference of the tire is 90”, you would divide 90” by 3.14, to which the answer is 28.66242”.  Industry standards would mark this tire as being 29” tall.