How to Maintain a Rolling Circumference

Drivers seldom consider that the distance they cover in their vehicle is a function of a single wheel rotation. One rotation of the wheel covers a distance called the rolling circumference of the tire. Maintaining a matched rolling circumference on your vehicle -- where all four wheels cover the same distance with each rotation -- requires that particular attention to be paid to the tires. Vehicle manufacturers typically recommend matching rolling circumferences of all four wheels. Failure to adhere to this recommendation may result in handling problems, regular tire replacement, or expensive repairs to the vehicle's drive-line.

• 1

  Consult your vehicle manual or the vehicle manufacturer to determine the tire matching requirements or rolling circumference recommendations for your vehicle, as this will influence how often tires should be replaced. For example, some manufacturers recommend a rolling circumference tolerance that allows all tire tread depths to be within a sixteenth of an inch, while others require the rolling radius of all four tires to be the same.

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  Tire pressure affects the rolling circumference. air pressure gauge image by Greg Pickens from Fotolia.com

  Check the inflation pressure of all tires regularly, using a tire pressure gauge. Adjust the pressure to match the manufacturer's recommendations which may be found in the vehicle manual or on a sticker attached to the door frame of the driver's door. The rolling circumference is influenced by tire pressure, and one or more over- or under-inflated tires may result in a mismatched rolling circumference for the vehicle.

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  Tread wear decreases the rolling circumference. Dangerous Tread Wear image by Scott Griessel from Fotolia.com

  Use a tread depth gauge to regularly measure the tread depth on all the tires. Uneven tread wear that exceeds the manufacturer's allowed difference in rolling circumference for the vehicle necessitates tire replacement.

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  Replace all the tires at the same time, if possible, using the same brand, tread design, and tread depth. Fit matched tires on each axle if the rolling circumference tolerance for the vehicle permits different tread depths on the front and rear axles. Where circumstances permit only one tire to be replaced, the excess tread on the new tire should be shaved so that the tread depth matches the worn tires on the vehicle.

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  Include the full-sized spare tire in all tire rotation patterns, starting with the first rotation. This will promote even tread wear on all the tires, and provide a well-matched replacement tire should one of working tires be damaged and need to be permanently replaced.