255/75R17 vs 285/70R17
285/70R17 is taller than 255/75R17 by 2.03% — a diameter difference of 0.65″.
What changes between 255/75R17 and 285/70R17
Switching from 255/75R17 to 285/70R17 changes overall diameter by +2.03%, a taller tire by 0.65 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 +1.18″ (255mm → 285mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.32″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -12, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 66.3 mph. Both sizes share the same 17″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 255/75R17 | 285/70R17 |
|---|---|---|
| Overall diameter | 32.06″ | 32.71″ |
| Section width | 10.04″ (255 mm) | 11.22″ (285 mm) |
| Sidewall height | 7.53″ (75%) | 7.85″ (70%) |
| Rim diameter | 17″ | 17″ |
| Circumference | 100.72″ | 102.76″ |
| Revs per mile | 629 | 617 |
Interactive comparison
275/65R18 or "33" for inch aliases255/75R17
- Diameter
- 32.06″ / 814.3mm
- Section Width
- 10.04″
- Sidewall
- 7.53″ / 191.25mm
- Circumference
- 100.72″
- Revs/Mile
- 629
285/70R17
- Diameter
- 32.71″ / 830.8mm
- Section Width
- 11.22″
- Sidewall
- 7.85″ / 199.5mm
- Circumference
- 102.76″
- Revs/Mile
- 617
Speedometer & Diameter Impact
Wider tire — verify wheel widthAt an indicated 60 mph, your actual speed is 61.22 mph (98.52 km/h). Your speedometer reads 2.03% low versus actual speed.