275/30ZR20 vs 245/35R20
245/35R20 is taller than 275/30ZR20 by 0.97% — a diameter difference of 0.25″.
What changes between 275/30ZR20 and 245/35R20
Switching from 275/30ZR20 to 245/35R20 changes overall diameter by +0.97%, a taller tire by 0.25 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″ (275mm → 245mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.13″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -7, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 65.6 mph. Both sizes share the same 20″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 275/30ZR20 | 245/35R20 |
|---|---|---|
| Overall diameter | 26.5″ | 26.75″ |
| Section width | 10.83″ (275 mm) | 9.65″ (245 mm) |
| Sidewall height | 3.25″ (30%) | 3.38″ (35%) |
| Rim diameter | 20″ | 20″ |
| Circumference | 83.24″ | 84.04″ |
| Revs per mile | 761 | 754 |
Interactive comparison
275/65R18 or "33" for inch aliases275/30ZR20
- Diameter
- 26.5″ / 673mm
- Section Width
- 10.83″
- Sidewall
- 3.25″ / 82.5mm
- Circumference
- 83.24″
- Revs/Mile
- 761
245/35R20
- Diameter
- 26.75″ / 679.5mm
- Section Width
- 9.65″
- Sidewall
- 3.38″ / 85.75mm
- Circumference
- 84.04″
- Revs/Mile
- 754
Speedometer & Diameter Impact
Narrower tire — verify wheel widthAt an indicated 60 mph, your actual speed is 60.58 mph (97.49 km/h). Your speedometer reads 0.97% low versus actual speed.