TireSizesFinder

285/35R19 vs 245/35R20

245/35R20 is 0.10 in (2.6 mm) shorter than 285/35R19, a −0.38% diameter difference. With the speedometer set for 285/35R19, an indicated 60 mph is 59.8 mph on 245/35R20.

Is this a safe swap?

Diameter difference −0.38%: under 1%

By overall diameter alone, 245/35R20 is a near match for 285/35R19; 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: 285/35R19 (26.85 in) vs 245/35R20 (26.75 in)285/35R1926.85 in × 11.22 in245/35R2026.75 in × 9.65 in
Side profile and tread width, drawn to the same scale.
285/35R19 vs 245/35R20 differences
Measurement285/35R19245/35R20Difference% diff
Overall diameter26.85 in (682.1 mm)26.75 in (679.5 mm)−0.10 in (−2.6 mm)−0.38%
Sidewall height3.93 in (99.8 mm)3.38 in (85.8 mm)−0.55 in (−14.0 mm)−14.04%
Section width11.22 in (285.0 mm)9.65 in (245.0 mm)−1.57 in (−40.0 mm)−14.04%
Circumference84.37 in (2,142.9 mm)84.04 in (2,134.7 mm)−0.32 in (−8.2 mm)−0.38%
Revolutions per mile751754+3+0.38%
True speed with the speedometer calibrated for 285/35R19
IndicatedActual on 285/35R19Actual on 245/35R20Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.8 mph−0.2 mph
75 mph75.0 mph74.7 mph−0.3 mph

Ride-height change: 245/35R20 lowers the vehicle by 0.05 in (1.3 mm) at the axle (half the −2.6 mm diameter difference).

245/35R20 is 0.10 in shorter than 285/35R19 and 40 mm narrower, a 0.38% difference in overall diameter.

With the speedometer calibrated for 285/35R19, an indicated 60 mph is actually 59.8 mph on 245/35R20, and revolutions per mile change from 751 to 754.

245/35R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 285/35R19.

Size pages

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