255/70R17 vs 285/65R17

285/65R17 is 0.53 in (13.5 mm) taller than 255/70R17, a +1.71% diameter difference. With the speedometer set for 255/70R17, an indicated 60 mph is 61.0 mph on 285/65R17.

Is this a safe swap?

Diameter difference +1.71%: within the ±3% guideline

By overall diameter alone, 285/65R17 falls inside the ±3% range commonly used as a guideline when replacing 255/70R17. 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.

255/70R17 vs 285/65R17 differences
Measurement	255/70R17	285/65R17	Difference	% diff
Overall diameter	31.06 in (788.8 mm)	31.59 in (802.3 mm)	+0.53 in (+13.5 mm)	+1.71%
Sidewall height	7.03 in (178.5 mm)	7.29 in (185.3 mm)	+0.27 in (+6.8 mm)	+3.78%
Section width	10.04 in (255.0 mm)	11.22 in (285.0 mm)	+1.18 in (+30.0 mm)	+11.76%
Circumference	97.56 in (2,478.1 mm)	99.23 in (2,520.5 mm)	+1.67 in (+42.4 mm)	+1.71%
Revolutions per mile	649	639	−11	−1.68%

True speed with the speedometer calibrated for 255/70R17
Indicated	Actual on 255/70R17	Actual on 285/65R17	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.0 mph	+1.0 mph
75 mph	75.0 mph	76.3 mph	+1.3 mph

Ride-height change: 285/65R17 raises the vehicle by 0.27 in (6.8 mm) at the axle (half the +13.5 mm diameter difference).

285/65R17 is 0.53 in taller than 255/70R17 and 30 mm wider, a 1.71% difference in overall diameter.

With the speedometer calibrated for 255/70R17, an indicated 60 mph is actually 61.0 mph on 285/65R17, and revolutions per mile change from 649 to 639.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 255/70R17

Other comparisons with 285/65R17

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