UPSIZING OR DOWNSIZING
You might ask: do bigger tires make your speedometer faster? The answer is no.
Tire size and speedometer accuracy are directly linked to each other.
Up-sizing, or installing a taller tire, will lead to a speedometer reading that displays slower than your actual speed. This is because a taller tire will have a larger overall circumference, causing it to need to travel more distance per revolution than the original equipment tire.
Downsizing, or installing a shorter tire, will cause the speedometer to display a faster speed than you are actually driving. This is because the smaller tire will have a smaller circumference, causing the tire to travel less distance per rotation than the original equipment tire.
Speedometer readings are altered by changing the tire height because most vehicles measure speed within the transmission based on tire revolutions.
You can enter your vehicle information here to review optional sizes of compatible tires and wheels.
PLUS SIZING
Plus sizing means replacing your original equipment tires with a tire that is a different size while having the same overall height and diameter. It can also mean replacing your original equipment wheels/rims with a larger or smaller size but maintaining the same tire height. Plus sizing should not interfere with speedometer accuracy.
Want to upgrade your tires? Call or make an online appointment for faster service!
HOW TO RECALIBRATE A SPEEDOMETER
America's Tire recommends that you recalibrate your speedometer every time you change your tire size. This is so you can safely operate on the road, ensuring you are not accidentally speeding or dangerously below the flow of traffic speed.
America's Tire does not offer recalibration, but encourages its customers to go to a professional auto shop that can do it for them. Drivers can recalibrate modern cars on their own using calibration settings on their vehicle’s computer and driving a prescribed distance to adjust the settings. However, for safety’s sake, it is better to go to professionals. Ask your America's Tire tech if they can refer you to an appropriate shop.
Tire Size and Speedometer Calculation
You can also manually calculate your speed. Using the road mile markers and a stopwatch to track the exact number of seconds it takes you to travel the distance of a single mile, you can calculate your speed. You will have to convert seconds to hours however to get a mile-per-hour metric. However, this is often less than accurate.
For a more accurate speed, use our tire size and speedometer calculator.
Your GPS device or mobile mapping app may also come equipped with a satellite speedometer function.
Do you still have questions about tire size and speedometer or maybe recalibration? Reach out to your local America's Tire store and we’ll get you taken care of. Just give us a call or make an appointment.
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