285/65R17 vs 235/80R17

235/80R17 is 0.22 in (5.5 mm) taller than 285/65R17, a +0.69% diameter difference. With the speedometer set for 285/65R17, an indicated 60 mph is 60.4 mph on 235/80R17.

Is this a safe swap?

Diameter difference +0.69%: under 1%

By overall diameter alone, 235/80R17 is a near match for 285/65R17; the speedometer changes by less than 1%. 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 235/80R17 differences
Measurement	285/65R17	235/80R17	Difference	% diff
Overall diameter	31.59 in (802.3 mm)	31.80 in (807.8 mm)	+0.22 in (+5.5 mm)	+0.69%
Sidewall height	7.29 in (185.3 mm)	7.40 in (188.0 mm)	+0.11 in (+2.8 mm)	+1.48%
Section width	11.22 in (285.0 mm)	9.25 in (235.0 mm)	−1.97 in (−50.0 mm)	−17.54%
Circumference	99.23 in (2,520.5 mm)	99.91 in (2,537.8 mm)	+0.68 in (+17.3 mm)	+0.69%
Revolutions per mile	639	634	−4	−0.68%

True speed with the speedometer calibrated for 285/65R17
Indicated	Actual on 285/65R17	Actual on 235/80R17	Difference
30 mph	30.0 mph	30.2 mph	+0.2 mph
60 mph	60.0 mph	60.4 mph	+0.4 mph
75 mph	75.0 mph	75.5 mph	+0.5 mph

Ride-height change: 235/80R17 raises the vehicle by 0.11 in (2.8 mm) at the axle (half the +5.5 mm diameter difference).

235/80R17 is 0.22 in taller than 285/65R17 and 50 mm narrower, a 0.69% difference in overall diameter.

With the speedometer calibrated for 285/65R17, an indicated 60 mph is actually 60.4 mph on 235/80R17, and revolutions per mile change from 639 to 634.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 285/65R17

Other comparisons with 235/80R17

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