265/55R20 vs 235/65R20
235/65R20 is taller than 265/55R20 by 1.75% — a diameter difference of 0.55″.
What changes between 265/55R20 and 235/65R20
Switching from 265/55R20 to 235/65R20 changes overall diameter by +1.75%, a taller tire by 0.55 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″ (265mm → 235mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.27″: 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 | 235/65R20 |
|---|---|---|
| Overall diameter | 31.48″ | 32.03″ |
| Section width | 10.43″ (265 mm) | 9.25″ (235 mm) |
| Sidewall height | 5.74″ (55%) | 6.01″ (65%) |
| Rim diameter | 20″ | 20″ |
| Circumference | 98.89″ | 100.62″ |
| 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
235/65R20
- Diameter
- 32.03″ / 813.5mm
- Section Width
- 9.25″
- Sidewall
- 6.01″ / 152.75mm
- Circumference
- 100.62″
- Revs/Mile
- 630
Speedometer & Diameter Impact
Narrower tire — verify wheel widthAt an indicated 60 mph, your actual speed is 61.05 mph (98.25 km/h). Your speedometer reads 1.75% low versus actual speed.