265/30R20 vs 285/30R20

285/30R20 is 0.47 in (12.0 mm) taller than 265/30R20, a +1.80% diameter difference. With the speedometer set for 265/30R20, an indicated 60 mph is 61.1 mph on 285/30R20.

Is this a safe swap?

Diameter difference +1.80%: within the ±3% guideline

By overall diameter alone, 285/30R20 falls inside the ±3% range commonly used as a guideline when replacing 265/30R20. 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.

265/30R20 vs 285/30R20 differences
Measurement	265/30R20	285/30R20	Difference	% diff
Overall diameter	26.26 in (667.0 mm)	26.73 in (679.0 mm)	+0.47 in (+12.0 mm)	+1.80%
Sidewall height	3.13 in (79.5 mm)	3.37 in (85.5 mm)	+0.24 in (+6.0 mm)	+7.55%
Section width	10.43 in (265.0 mm)	11.22 in (285.0 mm)	+0.79 in (+20.0 mm)	+7.55%
Circumference	82.50 in (2,095.4 mm)	83.98 in (2,133.1 mm)	+1.48 in (+37.7 mm)	+1.80%
Revolutions per mile	768	754	−14	−1.77%

True speed with the speedometer calibrated for 265/30R20
Indicated	Actual on 265/30R20	Actual on 285/30R20	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.1 mph	+1.1 mph
75 mph	75.0 mph	76.3 mph	+1.3 mph

Ride-height change: 285/30R20 raises the vehicle by 0.24 in (6.0 mm) at the axle (half the +12.0 mm diameter difference).

285/30R20 is 0.47 in taller than 265/30R20 and 20 mm wider, a 1.80% difference in overall diameter.

With the speedometer calibrated for 265/30R20, an indicated 60 mph is actually 61.1 mph on 285/30R20, and revolutions per mile change from 768 to 754.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 265/30R20

Other comparisons with 285/30R20

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