245/70R17 vs 255/70R17
Side-by-side comparison of overall diameter, sidewall height, speedometer error, and ride-height change.
Borderline — Check wheel-arch clearance and reset TPMS before fitting.
To scale
245/70R17
- Section width
- 245 mm
- Aspect ratio
- 70%
- Rim diameter
- 17"
- Sidewall
- 171.5 mm
- Overall diameter
- 774.8 mm
- Circumference
- 2434 mm
- Revs / mile
- 661
- Revs / km
- 411
255/70R17
- Section width
- 255 mm
- Aspect ratio
- 70%
- Rim diameter
- 17"
- Sidewall
- 178.5 mm
- Overall diameter
- 788.8 mm
- Circumference
- 2478 mm
- Revs / mile
- 649
- Revs / km
- 404
Difference
- Overall diameter
- +14.0 mm (+1.81%)
- Sidewall height
- +7.0 mm
- Tread width
- +10 mm
- Ride height (axle)
- +7.0 mm
- Speedometer error
- +1.81%
- At indicated 60 mph
- actual 61.1 mph
- At indicated 100 km/h
- actual 101.8 km/h
Will 255/70R17 fit instead of 245/70R17?
The overall diameter changes by 1.81%. Most manufacturers consider a swap acceptable when the difference stays under 3% — beyond that, you may see speedometer error, ABS/TPMS warnings, or wheel-well clearance problems. This page only covers the math; your vehicle's wheel arches, suspension geometry, and load rating still matter.
What the numbers mean
- Overall diameter — outside-to-outside height of the tire. Affects ride height, gearing, and speedometer calibration.
- Sidewall height — rubber from rim edge to tread. Lower sidewall gives sharper steering response but a harsher ride.
- Speedometer error — how far off your indicated speed will be after the swap. Positive means the speedo under-reads (actual speed is higher than shown).