275/65R18 vs 285/65R18
285/65R18 is taller than 275/65R18 by 1.60% — a diameter difference of 0.52″.
What changes between 275/65R18 and 285/65R18
Switching from 275/65R18 to 285/65R18 changes overall diameter by +1.60%, a taller tire by 0.52 inches. This lands inside the ±3% fitment safe zone, so most vehicles will accept the swap without rubbing, speedometer recalibration, or ABS/TPMS complications. Section width moves by +0.39″ (275mm → 285mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.25″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -10, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 66.0 mph. Both sizes share the same 18″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 275/65R18 | 285/65R18 |
|---|---|---|
| Overall diameter | 32.07″ | 32.59″ |
| Section width | 10.83″ (275 mm) | 11.22″ (285 mm) |
| Sidewall height | 7.04″ (65%) | 7.29″ (65%) |
| Rim diameter | 18″ | 18″ |
| Circumference | 100.77″ | 102.37″ |
| Revs per mile | 629 | 619 |
Interactive comparison
275/65R18 or "33" for inch aliases275/65R18
- Diameter
- 32.07″ / 814.7mm
- Section Width
- 10.83″
- Sidewall
- 7.04″ / 178.75mm
- Circumference
- 100.77″
- Revs/Mile
- 629
285/65R18
- Diameter
- 32.59″ / 827.7mm
- Section Width
- 11.22″
- Sidewall
- 7.29″ / 185.25mm
- Circumference
- 102.37″
- Revs/Mile
- 619
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 60.96 mph (98.1 km/h). Your speedometer reads 1.60% low versus actual speed.