245/30R19 vs 255/30R19
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
245/30R19
- Section width
- 245 mm
- Aspect ratio
- 30%
- Rim diameter
- 19"
- Sidewall
- 73.5 mm
- Overall diameter
- 629.6 mm
- Circumference
- 1978 mm
- Revs / mile
- 814
- Revs / km
- 506
255/30R19
- Section width
- 255 mm
- Aspect ratio
- 30%
- Rim diameter
- 19"
- Sidewall
- 76.5 mm
- Overall diameter
- 635.6 mm
- Circumference
- 1997 mm
- Revs / mile
- 806
- Revs / km
- 501
Difference
- Overall diameter
- +6.0 mm (+0.95%)
- Sidewall height
- +3.0 mm
- Tread width
- +10 mm
- Ride height (axle)
- +3.0 mm
- Speedometer error
- +0.95%
- At indicated 60 mph
- actual 60.6 mph
- At indicated 100 km/h
- actual 101.0 km/h
Will 255/30R19 fit instead of 245/30R19?
The overall diameter changes by 0.95%. 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).