235/60R18 vs 255/50R19
Comparison of overall diameter, sidewall, speedometer error, and ride-height change between these two tire sizes.
235/60R18
- Section width
- 235 mm
- Aspect ratio
- 60%
- Rim
- 18"
- Sidewall
- 141.0 mm
- Overall diameter
- 739.2 mm
- Revs / mile
- 693
255/50R19
- Section width
- 255 mm
- Aspect ratio
- 50%
- Rim
- 19"
- Sidewall
- 127.5 mm
- Overall diameter
- 737.6 mm
- Revs / mile
- 695
Difference
- Overall diameter
- -1.6 mm (-0.22%)
- Sidewall
- -13.5 mm
- Tread width
- +20 mm
- Ride height (axle)
- -0.8 mm
- Speedometer error
- -0.22%
- At indicated 60 mph
- actual 59.87 mph
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 is the outside-to-outside height of the tire. Affects ride height, gearing, and speedometer.
- Sidewall is the height of the rubber from rim to tread. Lower sidewall = sharper steering, harsher ride.
- Speedometer error is the percentage your indicated speed will be off after the swap (positive = speedo reads lower than actual).