TireSizesFinder

245/35R18 vs 255/30R19

255/30R19 is 0.27 in (6.9 mm) taller than 245/35R18, a +1.10% diameter difference. With the speedometer set for 245/35R18, an indicated 60 mph is 60.7 mph on 255/30R19.

Is this a safe swap?

Diameter difference +1.10%: within the ±3% guideline

By overall diameter alone, 255/30R19 falls inside the ±3% range commonly used as a guideline when replacing 245/35R18. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 245/35R18 (24.75 in) vs 255/30R19 (25.02 in)245/35R1824.75 in × 9.65 in255/30R1925.02 in × 10.04 in
Side profile and tread width, drawn to the same scale.
245/35R18 vs 255/30R19 differences
Measurement245/35R18255/30R19Difference% diff
Overall diameter24.75 in (628.7 mm)25.02 in (635.6 mm)+0.27 in (+6.9 mm)+1.10%
Sidewall height3.38 in (85.8 mm)3.01 in (76.5 mm)−0.36 in (−9.2 mm)−10.79%
Section width9.65 in (245.0 mm)10.04 in (255.0 mm)+0.39 in (+10.0 mm)+4.08%
Circumference77.76 in (1,975.1 mm)78.61 in (1,996.8 mm)+0.85 in (+21.7 mm)+1.10%
Revolutions per mile815806−9−1.09%
True speed with the speedometer calibrated for 245/35R18
IndicatedActual on 245/35R18Actual on 255/30R19Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.7 mph+0.7 mph
75 mph75.0 mph75.8 mph+0.8 mph

Ride-height change: 255/30R19 raises the vehicle by 0.14 in (3.4 mm) at the axle (half the +6.9 mm diameter difference).

255/30R19 is 0.27 in taller than 245/35R18 and 10 mm wider, a 1.10% difference in overall diameter.

With the speedometer calibrated for 245/35R18, an indicated 60 mph is actually 60.7 mph on 255/30R19, and revolutions per mile change from 815 to 806.

255/30R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 245/35R18.

Size pages

Other comparisons with 245/35R18

Other comparisons with 255/30R19

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.