Diameter
724.3 → 737.3 mm
Tire Size Toolbox
Tire Size Calculator: Compare Two Tire Sizes
Compare two tire sizes before you buy. See how a new size can change diameter, ground clearance, and your speedometer reading.
Compare my tiresFree tire size calculator
Compare two tire sizes
Enter the tire on your car first, then the tire you are considering. Use a format like 225/65R17.
Your result: the new tire is 1.8% larger
This changes the tire diameter by 13 mm. The numbers below are estimates based on tire-size math.
Visual size check
See the diameter difference
Close size matchThe diameter difference is small. Still check the tire and vehicle specifications.
Circumference
2,275.5 → 2,316.3 mm
Ground clearance
+6.5 mm
Revolutions per mile
707.3 → 694.8
Speedometer estimate
If your speedometer was set for the current tire, this is the road speed when it shows:
| Speedometer shows | Actual road speed |
|---|---|
| 30 mph | 30.5 mph |
| 60 mph | 61.1 mph |
| 70 mph | 71.3 mph |
How to read a tire size
A size such as 225/65R17 tells you three things: 225 is the tire width in millimeters, 65 is the sidewall height as a percent of its width, and 17 is the wheel size in inches.
Changing any of these numbers can change how much the tire turns in one trip around the wheel. That is why a different tire size can affect clearance and the speed your car reports.
How to compare tire sizes
- Find your current tire size. It is printed on the tire sidewall, usually in a format such as 225/65R17.
- Enter the new tire size. Use the same format in the second box.
- Check the result. Start with diameter and speedometer estimates, then use the visual size check to see the change.
- Confirm fitment before buying. Tire-size math cannot check wheel width, rubbing, load rating, or the space inside your vehicle's wheel well.
Tire size calculator FAQ
What does a tire size calculator show?
It uses the numbers in two tire sizes to estimate the difference in diameter, circumference, ground clearance, revolutions per mile, and speedometer reading.
Will a bigger tire make my speedometer read wrong?
Usually, yes. A taller tire travels farther with each turn, so your actual road speed can be higher than the speed shown on a speedometer set for the old tire size.
Does a larger tire give more ground clearance?
Yes, but only by half of the total diameter change. For example, a tire that is 20 mm taller can raise ground clearance by about 10 mm.
Does this tool confirm that a tire will fit?
No. It is a size-math estimate, not a fitment approval. Check the owner's manual, the exact tire specifications, clearance while turning, and tire load and speed ratings.