235/85R16 vs 255/75R17

255/75R17 is 0.33 in (8.4 mm) taller than 235/85R16, a +1.04% diameter difference. With the speedometer set for 235/85R16, an indicated 60 mph is 60.6 mph on 255/75R17.

Is this a safe swap?

Diameter difference +1.04%: within the ±3% guideline

By overall diameter alone, 255/75R17 falls inside the ±3% range commonly used as a guideline when replacing 235/85R16. 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.

235/85R16 vs 255/75R17 differences
Measurement	235/85R16	255/75R17	Difference	% diff
Overall diameter	31.73 in (805.9 mm)	32.06 in (814.3 mm)	+0.33 in (+8.4 mm)	+1.04%
Sidewall height	7.86 in (199.8 mm)	7.53 in (191.3 mm)	−0.33 in (−8.5 mm)	−4.26%
Section width	9.25 in (235.0 mm)	10.04 in (255.0 mm)	+0.79 in (+20.0 mm)	+8.51%
Circumference	99.68 in (2,531.8 mm)	100.72 in (2,558.2 mm)	+1.04 in (+26.4 mm)	+1.04%
Revolutions per mile	636	629	−7	−1.03%

True speed with the speedometer calibrated for 235/85R16
Indicated	Actual on 235/85R16	Actual on 255/75R17	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.8 mph	+0.8 mph

Ride-height change: 255/75R17 raises the vehicle by 0.17 in (4.2 mm) at the axle (half the +8.4 mm diameter difference).

255/75R17 is 0.33 in taller than 235/85R16 and 20 mm wider, a 1.04% difference in overall diameter.

With the speedometer calibrated for 235/85R16, an indicated 60 mph is actually 60.6 mph on 255/75R17, and revolutions per mile change from 636 to 629.

255/75R17 mounts on a 17-inch wheel, a plus-1 fitment from the 16-inch wheel of 235/85R16.

Size pages

Other comparisons with 235/85R16

Other comparisons with 255/75R17

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