275/50R20 vs 285/50R20

285/50R20 is 0.39 in (10.0 mm) taller than 275/50R20, a +1.28% diameter difference. With the speedometer set for 275/50R20, an indicated 60 mph is 60.8 mph on 285/50R20.

Is this a safe swap?

Diameter difference +1.28%: within the ±3% guideline

By overall diameter alone, 285/50R20 falls inside the ±3% range commonly used as a guideline when replacing 275/50R20. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

275/50R20 vs 285/50R20 differences
Measurement	275/50R20	285/50R20	Difference	% diff
Overall diameter	30.83 in (783.0 mm)	31.22 in (793.0 mm)	+0.39 in (+10.0 mm)	+1.28%
Sidewall height	5.41 in (137.5 mm)	5.61 in (142.5 mm)	+0.20 in (+5.0 mm)	+3.64%
Section width	10.83 in (275.0 mm)	11.22 in (285.0 mm)	+0.39 in (+10.0 mm)	+3.64%
Circumference	96.85 in (2,459.9 mm)	98.08 in (2,491.3 mm)	+1.24 in (+31.4 mm)	+1.28%
Revolutions per mile	654	646	−8	−1.26%

True speed with the speedometer calibrated for 275/50R20
Indicated	Actual on 275/50R20	Actual on 285/50R20	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	76.0 mph	+1.0 mph

Ride-height change: 285/50R20 raises the vehicle by 0.20 in (5.0 mm) at the axle (half the +10.0 mm diameter difference).

285/50R20 is 0.39 in taller than 275/50R20 and 10 mm wider, a 1.28% difference in overall diameter.

With the speedometer calibrated for 275/50R20, an indicated 60 mph is actually 60.8 mph on 285/50R20, and revolutions per mile change from 654 to 646.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 275/50R20

Other comparisons with 285/50R20

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.