235/60R18 vs 255/50R19
Side-by-side comparison of overall diameter, sidewall height, speedometer error, and ride-height change.
Safe to swap — Diameter difference is under 1.5% — within normal tolerance.
To scale
235/60R18
- Section width
- 235 mm
- Aspect ratio
- 60%
- Rim diameter
- 18"
- Sidewall
- 141.0 mm
- Overall diameter
- 739.2 mm
- Circumference
- 2322 mm
- Revs / mile
- 693
- Revs / km
- 431
255/50R19
- Section width
- 255 mm
- Aspect ratio
- 50%
- Rim diameter
- 19"
- Sidewall
- 127.5 mm
- Overall diameter
- 737.6 mm
- Circumference
- 2317 mm
- Revs / mile
- 695
- Revs / km
- 432
Difference
- Overall diameter
- -1.6 mm (-0.22%)
- Sidewall height
- -13.5 mm
- Tread width
- +20 mm
- Ride height (axle)
- -0.8 mm
- Speedometer error
- -0.22%
- At indicated 60 mph
- actual 59.9 mph
- At indicated 100 km/h
- actual 99.8 km/h
Will 255/50R19 fit instead of 235/60R18?
The overall diameter changes by 0.22%. 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).