285/65R17 vs 255/75R17

255/75R17 is 0.47 in (12.0 mm) taller than 285/65R17, a +1.50% diameter difference. With the speedometer set for 285/65R17, an indicated 60 mph is 60.9 mph on 255/75R17.

Is this a safe swap?

Diameter difference +1.50%: within the ±3% guideline

By overall diameter alone, 255/75R17 falls inside the ±3% range commonly used as a guideline when replacing 285/65R17. 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.

285/65R17 vs 255/75R17 differences
Measurement	285/65R17	255/75R17	Difference	% diff
Overall diameter	31.59 in (802.3 mm)	32.06 in (814.3 mm)	+0.47 in (+12.0 mm)	+1.50%
Sidewall height	7.29 in (185.3 mm)	7.53 in (191.3 mm)	+0.24 in (+6.0 mm)	+3.24%
Section width	11.22 in (285.0 mm)	10.04 in (255.0 mm)	−1.18 in (−30.0 mm)	−10.53%
Circumference	99.23 in (2,520.5 mm)	100.72 in (2,558.2 mm)	+1.48 in (+37.7 mm)	+1.50%
Revolutions per mile	639	629	−9	−1.47%

True speed with the speedometer calibrated for 285/65R17
Indicated	Actual on 285/65R17	Actual on 255/75R17	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.9 mph	+0.9 mph
75 mph	75.0 mph	76.1 mph	+1.1 mph

Ride-height change: 255/75R17 raises the vehicle by 0.24 in (6.0 mm) at the axle (half the +12.0 mm diameter difference).

255/75R17 is 0.47 in taller than 285/65R17 and 30 mm narrower, a 1.50% difference in overall diameter.

With the speedometer calibrated for 285/65R17, an indicated 60 mph is actually 60.9 mph on 255/75R17, and revolutions per mile change from 639 to 629.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 285/65R17

Other comparisons with 255/75R17

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