Automotive Calculators
Tire Comparison Calculator
Compare your original tire size to a new size. See the diameter difference and speedometer error before making the switch.
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Tire Sizes
Original Tire
New Tire
Original
26.31"
668.3 mm
New
25.86"
656.8 mm
Diameter Diff
-11.5 mm
size change
Size Change %
-1.7%
relative change
Speedometer Error
-1.7%
Actual speed at indicated 100: 98.3
Speedometer error above ±3% may be illegal in some jurisdictions. Always verify fitment with a wheel and tire specialist.
Why Compare Tire Sizes?
Changing tire sizes affects speedometer accuracy, odometer readings, clearance, load capacity, and ride quality. This calculator helps you verify fitment compatibility before purchasing new tires.