Tire Size Calculator: Compare, Convert, and Confirm Fitment
Use our tire size calculator to see exact, side‑by‑side measurements for your current (OE) and potential replacement tires. Enter your sizes to view sidewall height, section width, overall diameter, circumference, and estimated revolutions per mile—plus how a size change can affect your speedometer.
How to use the calculator
Find your current tire size on the sidewall (or in your owner’s manual).
Enter your current and new sizes. The calculator returns:
Sidewall height
Section width
Overall diameter and circumference
Estimated revolutions per mile
An estimated true speed based on the size change
Example comparison (from the page):
- Current: 205/60R16
- New: 225/50R17
- Differences shown by the calculator:
- Rev./Mile: 785.32 vs 779.91 (difference −5.41)
- Section Width: 8.07" vs 8.86" (difference +0.79")
- Sidewall Height: 4.84" vs 4.43" (difference −0.41")
- Circumference: 80.68" vs 81.24" (difference +0.56")
- Tire Height: 25.68" vs 25.86" (difference +0.18")
When ready, you can quickly browse options for any size:
- Shop tires by size
- Shop wheels by size
Verify wheels and tires will fit your vehicle
For vehicle‑specific fitment, enter your details in My Vehicles to ensure products fit your car or truck.
The calculator helps you see which optional tire sizes work on your vehicle and how wheel size changes can affect your speedometer.
Always confirm any new tire meets your vehicle’s load and speed requirements. Learn more about Original Equipment (OE) tires.
Looking for mud‑terrain or all‑terrain tires measured in inches? See our flotation tire size chart for size dimensions and specs presented in inch‑based format.
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Disclaimers
The calculator results are based on the mathematical equations of the sizes entered, not the specifications provided by the tire manufacturer. Please refer to the guides supplied by the manufacturers for exact specifications.
Check the manufacturer requirements to make sure any new tires meet the load and speed needs of your vehicle before installing tires that are larger or smaller than the original equipment tires.