295/45ZR20 vs 255/55R20
255/55R20 is taller than 295/45ZR20 by 1.94% — a diameter difference of 0.59″.
What changes between 295/45ZR20 and 255/55R20
Switching from 295/45ZR20 to 255/55R20 changes overall diameter by +1.94%, a taller tire by 0.59 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 -1.57″ (295mm → 255mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.29″: 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 20″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 295/45ZR20 | 255/55R20 |
|---|---|---|
| Overall diameter | 30.45″ | 31.04″ |
| Section width | 11.61″ (295 mm) | 10.04″ (255 mm) |
| Sidewall height | 5.23″ (45%) | 5.52″ (55%) |
| Rim diameter | 20″ | 20″ |
| Circumference | 95.67″ | 97.53″ |
| Revs per mile | 662 | 650 |
Interactive comparison
275/65R18 or "33" for inch aliases295/45ZR20
- Diameter
- 30.45″ / 773.5mm
- Section Width
- 11.61″
- Sidewall
- 5.23″ / 132.75mm
- Circumference
- 95.67″
- Revs/Mile
- 662
255/55R20
- Diameter
- 31.04″ / 788.5mm
- Section Width
- 10.04″
- Sidewall
- 5.52″ / 140.25mm
- Circumference
- 97.53″
- Revs/Mile
- 650
Speedometer & Diameter Impact
Narrower tire — verify wheel widthAt an indicated 60 mph, your actual speed is 61.16 mph (98.43 km/h). Your speedometer reads 1.94% low versus actual speed.