265/55R20 vs 305/50R20
305/50R20 is taller than 265/55R20 by 1.69% — a diameter difference of 0.53″.
What changes between 265/55R20 and 305/50R20
Switching from 265/55R20 to 305/50R20 changes overall diameter by +1.69%, a taller tire by 0.53 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 +1.58″ (265mm → 305mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.26″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -11, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 66.1 mph. Both sizes share the same 20″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 265/55R20 | 305/50R20 |
|---|---|---|
| Overall diameter | 31.48″ | 32.01″ |
| Section width | 10.43″ (265 mm) | 12.01″ (305 mm) |
| Sidewall height | 5.74″ (55%) | 6″ (50%) |
| Rim diameter | 20″ | 20″ |
| Circumference | 98.89″ | 100.56″ |
| Revs per mile | 641 | 630 |
Interactive comparison
275/65R18 or "33" for inch aliases265/55R20
- Diameter
- 31.48″ / 799.5mm
- Section Width
- 10.43″
- Sidewall
- 5.74″ / 145.75mm
- Circumference
- 98.89″
- Revs/Mile
- 641
305/50R20
- Diameter
- 32.01″ / 813mm
- Section Width
- 12.01″
- Sidewall
- 6″ / 152.5mm
- Circumference
- 100.56″
- Revs/Mile
- 630
Speedometer & Diameter Impact
Wider tire — verify wheel widthAt an indicated 60 mph, your actual speed is 61.01 mph (98.19 km/h). Your speedometer reads 1.69% low versus actual speed.