235/65R17 vs 235/60R18
A calculated comparison of tire dimensions, speedometer change and clearance.
Last checked 12 October 2026Published by Sidewall GuideFormulas follow the Tire and Rim Association and ETRTO size conventions
Within 3%: a common safe change
A similar diameter does not confirm fitment. Check load index, wheel width and clearance.
| Dimension | Current | New | Difference |
|---|---|---|---|
| Overall diameter | 29.03 in (737 mm) | 29.10 in (739 mm) | +0.07 in (+0.3%) |
| Section width | 9.25 in (235 mm) | 9.25 in (235 mm) | 0.00 in (0.0%) |
| Sidewall height | 6.01 in (153 mm) | 5.55 in (141 mm) | −0.46 in (−7.7%) |
| Circumference | 91.19 in (2,316 mm) | 91.43 in (2,322 mm) | +0.24 in (+0.3%) |
| Revolutions per mile | 695 | 693 | −2 (−0.3%) |
Your speedometer
When your speedometer reads 30 / 45 / 60 / 75 mph, you are really doing …
| Speedometer reads | You are really doing |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.2 mph |
| 75 mph | 75.2 mph |
Your speedometer will read low: you are going faster than it shows.
Your odometer will count 1,000 miles when you have driven 1,003 miles.
Clearance
Ride height: +0.04 in
Tread edge: no change, on the same wheel offset
Ride height is half the diameter change. The width change splits equally to each side of the tire.
Fitment
Can I fit 235/60R18 instead of 235/65R17?
The calculated overall diameter changes by 0.07 in (0.3%). That is within 3%, a common size-change guideline. This calculation cannot confirm fitment for a specific vehicle.
Plus-sizing
Other sizes near 235/65R17
Common sizes on the same wheel and on +1 and +2 wheels whose overall diameter stays within 3% of 235/65R17's 29.03 in.
Same wheel17 in wheel
+118 in wheel
Next step
Compare your own sizes
Use the calculator with both sizes prefilled, then change either value to match your vehicle or replacement tire.
Compare your own sizes