235/60R18 vs 235/65R18 at a glance
| Measure | 235/60R18 (current) | 235/65R18 (new) | Difference |
|---|---|---|---|
| Overall height | 29.10 in | 30.03 in | +0.93 in (+3.18%) |
| Width | 9.25 in (235 mm) | 9.25 in (235 mm) | +0 mm |
| Sidewall | 5.55 in | 6.01 in | +0.46 in |
| Wheel | 18 in | 18 in | +0 in |
| Circumference | 91.4 in | 94.3 in | +2.9 in |
| Revs per mile | 693.0 | 671.7 | −21.4 |
Verdict: check clearance and speedometer
Over 3% and up to 5%: worth checking clearance, the speedometer and gearing before you buy. Going from 235/60R18 to 235/65R18 is a 3.2% increase in overall height (+0.93 in), and the vehicle sits about 0.46 in higher. The tire is the same width. The 3% rule of thumb comes from Discount Tire and 1010tires; it is not a guarantee of fit.
True speed and odometer
| Speedometer shows | You are really doing | Difference |
|---|---|---|
| 35 mph | 36.1 mph | +1.1 mph |
| 45 mph | 46.4 mph | +1.4 mph |
| 55 mph | 56.7 mph | +1.7 mph |
| 60 mph | 61.9 mph | +1.9 mph |
| 65 mph | 67.1 mph | +2.1 mph |
| 70 mph | 72.2 mph | +2.2 mph |
| 75 mph | 77.4 mph | +2.4 mph |
Odometer: 1,000 indicated miles is 1,032 real miles, and 10,000 is 10,318.
The math
235/60R18: 18 + 2 × (235 × 60% ÷ 25.4) = 29.10 in. 235/65R18: 18 + 2 × (235 × 65% ÷ 25.4) = 30.03 in. Change = 30.03 ÷ 29.10 − 1 = +3.18%. True speed at 60 = 60 × 30.03 ÷ 29.10 = 61.91 mph.
Check next
- Regear and RPM at cruise for this swap
- Speedometer and odometer correction
- Other sizes within ±3% of 235/60R18
Calculated from the size alone. Real tires vary a little by brand and model, and the loaded radius is a bit smaller. Confirm the wheel width range, clearance, load index and speed rating for your vehicle. See how to read a tire size, the load index chart and the speed rating chart.
Size pages: 235/60R18 · 235/65R18. More swaps: all tire size comparisons.