How Will Bigger Tires Affect My Speedometer?

By Staff WriterLast Updated Apr 15, 2020 6:09:49 PM ET
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Bigger tires will cause your speedometer to register a speed that is slower than your actual speed. For example, if your speedometer says 35 miles per hour on 20-inch diameter tires, changing to 23-inch diameter tires will make your true speed 40.25 mph, even though your speedometer will still show 35 mph.