TireSizesFinder

285/35R18 vs 285/30R19

285/30R19 is 0.12 in (3.1 mm) shorter than 285/35R18, a −0.47% diameter difference. With the speedometer set for 285/35R18, an indicated 60 mph is 59.7 mph on 285/30R19.

Is this a safe swap?

Diameter difference −0.47%: under 1%

By overall diameter alone, 285/30R19 is a near match for 285/35R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 285/35R18 (25.85 in) vs 285/30R19 (25.73 in)285/35R1825.85 in × 11.22 in285/30R1925.73 in × 11.22 in
Side profile and tread width, drawn to the same scale.
285/35R18 vs 285/30R19 differences
Measurement285/35R18285/30R19Difference% diff
Overall diameter25.85 in (656.7 mm)25.73 in (653.6 mm)−0.12 in (−3.1 mm)−0.47%
Sidewall height3.93 in (99.8 mm)3.37 in (85.5 mm)−0.56 in (−14.2 mm)−14.29%
Section width11.22 in (285.0 mm)11.22 in (285.0 mm)0.00 in (0.0 mm)0.00%
Circumference81.22 in (2,063.1 mm)80.84 in (2,053.3 mm)−0.38 in (−9.7 mm)−0.47%
Revolutions per mile780784+4+0.47%
True speed with the speedometer calibrated for 285/35R18
IndicatedActual on 285/35R18Actual on 285/30R19Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.7 mph−0.3 mph
75 mph75.0 mph74.6 mph−0.4 mph

Ride-height change: 285/30R19 lowers the vehicle by 0.06 in (1.6 mm) at the axle (half the −3.1 mm diameter difference).

285/30R19 is 0.12 in shorter than 285/35R18 and the same width, a 0.47% difference in overall diameter.

With the speedometer calibrated for 285/35R18, an indicated 60 mph is actually 59.7 mph on 285/30R19, and revolutions per mile change from 780 to 784.

285/30R19 mounts on a 19-inch wheel, a plus-1 fitment from the 18-inch wheel of 285/35R18.

Size pages

Other comparisons with 285/35R18

Other comparisons with 285/30R19

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