255/35ZR21 vs 295/35R21
295/35R21 is taller than 255/35ZR21 by 3.93% — a diameter difference of 1.10″.
What changes between 255/35ZR21 and 295/35R21
Switching from 255/35ZR21 to 295/35R21 changes overall diameter by +3.93%, a taller tire by 1.10 inches. This sits in the 3–5% caution band, where rubbing at full steering lock or suspension compression becomes possible. Leveling kits or fender-liner trims are often needed on lifted trucks. Section width moves by +1.57″ (255mm → 295mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.55″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -28, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 67.6 mph. Both sizes share the same 21″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 255/35ZR21 | 295/35R21 |
|---|---|---|
| Overall diameter | 28.03″ | 29.13″ |
| Section width | 10.04″ (255 mm) | 11.61″ (295 mm) |
| Sidewall height | 3.51″ (35%) | 4.06″ (35%) |
| Rim diameter | 21″ | 21″ |
| Circumference | 88.05″ | 91.51″ |
| Revs per mile | 720 | 692 |
Interactive comparison
275/65R18 or "33" for inch aliases255/35ZR21
- Diameter
- 28.03″ / 711.9mm
- Section Width
- 10.04″
- Sidewall
- 3.51″ / 89.25mm
- Circumference
- 88.05″
- Revs/Mile
- 720
295/35R21
- Diameter
- 29.13″ / 739.9mm
- Section Width
- 11.61″
- Sidewall
- 4.06″ / 103.25mm
- Circumference
- 91.51″
- Revs/Mile
- 692
Speedometer & Diameter Impact
Wider tire — verify wheel widthAt an indicated 60 mph, your actual speed is 62.36 mph (100.36 km/h). Your speedometer reads 3.93% low versus actual speed.