275/65R18 vs 285/65R18 at a glance
| Measure | 275/65R18 (current) | 285/65R18 (new) | Difference |
|---|---|---|---|
| Overall height | 32.07 in | 32.59 in | +0.51 in (+1.60%) |
| Width | 10.83 in (275 mm) | 11.22 in (285 mm) | +10 mm |
| Sidewall | 7.04 in | 7.29 in | +0.26 in |
| Wheel | 18 in | 18 in | +0 in |
| Circumference | 100.8 in | 102.4 in | +1.6 in |
| Revs per mile | 628.8 | 618.9 | −9.9 |
Verdict: close match
Within the 3% rule of thumb, so the speedometer, gearing and ride height change little. Going from 275/65R18 to 285/65R18 is a 1.6% increase in overall height (+0.51 in), and the vehicle sits about 0.26 in higher. The tire is 10 mm wider. 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 | 35.6 mph | +0.6 mph |
| 45 mph | 45.7 mph | +0.7 mph |
| 55 mph | 55.9 mph | +0.9 mph |
| 60 mph | 61.0 mph | +1.0 mph |
| 65 mph | 66.0 mph | +1.0 mph |
| 70 mph | 71.1 mph | +1.1 mph |
| 75 mph | 76.2 mph | +1.2 mph |
Odometer: 1,000 indicated miles is 1,016 real miles, and 10,000 is 10,160.
The math
275/65R18: 18 + 2 × (275 × 65% ÷ 25.4) = 32.07 in. 285/65R18: 18 + 2 × (285 × 65% ÷ 25.4) = 32.59 in. Change = 32.59 ÷ 32.07 − 1 = +1.60%. True speed at 60 = 60 × 32.59 ÷ 32.07 = 60.96 mph.
Check next
- Regear and RPM at cruise for this swap
- Speedometer and odometer correction
- Other sizes within ±3% of 275/65R18
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: 275/65R18 · 285/65R18. More swaps: all tire size comparisons.