Tire Size Comparison
Compare two sizes and see the effect on ride height and speed.
Your results
Compare the original and new sizes to see dimensional changes and approximate speedometer effect.
How the calculation works
Sidewall height = width × aspect ratio ÷ 100. Wheel diameter = rim diameter × 25.4. Overall diameter = wheel diameter + 2 × sidewall height. Circumference = π × overall diameter.
With circumference in millimetres, revolutions per kilometre = 1,000,000 ÷ circumference. Revolutions per mile = 1,609,344 ÷ circumference.
Percentage change = (new diameter ÷ original diameter − 1) × 100. Ride-height change is half the diameter change. Approximate true speed = indicated speed × new diameter ÷ original diameter, assuming the original calibration was exact.
These are nominal, unloaded dimensions. Actual rolling circumference varies with tire construction, wear, load and inflation. A similar diameter does not guarantee safe fitment or legal approval. Confirm manufacturer-approved sizes, load and speed ratings, wheel compatibility and clearance.