265/50R20 vs 255/55R20
255/55R20 is taller than 265/50R20 by 2.01% — a diameter difference of 0.61″.
What changes between 265/50R20 and 255/55R20
Switching from 265/50R20 to 255/55R20 changes overall diameter by +2.01%, a taller tire by 0.61 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″ (265mm → 255mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.30″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -13, 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 | 265/50R20 | 255/55R20 |
|---|---|---|
| Overall diameter | 30.43″ | 31.04″ |
| Section width | 10.43″ (265 mm) | 10.04″ (255 mm) |
| Sidewall height | 5.22″ (50%) | 5.52″ (55%) |
| Rim diameter | 20″ | 20″ |
| Circumference | 95.61″ | 97.53″ |
| Revs per mile | 663 | 650 |
Interactive comparison
275/65R18 or "33" for inch aliases265/50R20
- Diameter
- 30.43″ / 773mm
- Section Width
- 10.43″
- Sidewall
- 5.22″ / 132.5mm
- Circumference
- 95.61″
- Revs/Mile
- 663
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
At an indicated 60 mph, your actual speed is 61.2 mph (98.5 km/h). Your speedometer reads 2.01% low versus actual speed.