How Tread Wear and Tire Pressure Affects Speed

Most drivers realize that tire wear can affect traction and even fuel efficiency, but what few recognize is that worn-out tires can also affect the accuracy of your speedometer.

Your speedometer assumes your car is using the standard size tire for the make and model and calculates your speed based on the rotation of the axis. As tires wear out, the circumference (the distance around the outside of the tire) decreases. As such, each rotation of the axle moves the car less distance than it would have with a full tire.

For example, if your car uses a tire with a 24-inch diameter, it would have a circumference of 75.36 inches. If the tire loses ½ inch from wear, the total circumference would decrease to 73.79 inches (a 2% difference), and would require 1.02 rotations to go the same distance a brand new tire covers in one rotation. In terms of speed, this means that when your speedometer reads 60 mph the car is really only going 58.8 mph.

The inverse can occur if you overinflate your tires. If you overinflate your 24-inch tires so that they are a half-inch larger in diameter, your speedometer will read 60 mph, but the vehicle will actually be traveling at 61.2 mph. It doesn’t seem like a huge deal, but this could be the difference between going 10 mph over the limit (a $150 ticket) and 11 mph over the limit (a $300 ticket).

The good news is that neither worn out nor overinflated tires are likely to land you an unjustified speeding ticket. The bad news is you can’t use either as an excuse to fight a speeding ticket.

In New York, a speeding ticket costs at least $150, plus surcharges, and if you end up with six points or more on your license, you could also be required to pay a driver responsibility assessment of $100. At speeding ticket also carries at least three points on your license and can cause your insurance rates to skyrocket by hundreds of dollars.

If you or a loved one has been caught speeding, it is advisable that you imperative an attorney to help you avoid the costs associated with a ticket. The lawyers of the Rosenblum Law Firm are skilled New York traffic ticket attorneys who are experienced in handling tickets for speeding as well as other driving-related offenses. Call 888-203-2619 or email the Rosenblum Law Firm today for a free consultation about your case.


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