265/70R17 vs 235/80R17

235/80R17 is 0.20 in (5.0 mm) taller than 265/70R17, a +0.62% diameter difference. With the speedometer set for 265/70R17, an indicated 60 mph is 60.4 mph on 235/80R17.

Is this a safe swap?

Diameter difference +0.62%: under 1%

By overall diameter alone, 235/80R17 is a near match for 265/70R17; 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.

265/70R17 vs 235/80R17 differences
Measurement	265/70R17	235/80R17	Difference	% diff
Overall diameter	31.61 in (802.8 mm)	31.80 in (807.8 mm)	+0.20 in (+5.0 mm)	+0.62%
Sidewall height	7.30 in (185.5 mm)	7.40 in (188.0 mm)	+0.10 in (+2.5 mm)	+1.35%
Section width	10.43 in (265.0 mm)	9.25 in (235.0 mm)	−1.18 in (−30.0 mm)	−11.32%
Circumference	99.29 in (2,522.1 mm)	99.91 in (2,537.8 mm)	+0.62 in (+15.7 mm)	+0.62%
Revolutions per mile	638	634	−4	−0.62%

True speed with the speedometer calibrated for 265/70R17
Indicated	Actual on 265/70R17	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 0.10 in (2.5 mm) at the axle (half the +5.0 mm diameter difference).

235/80R17 is 0.20 in taller than 265/70R17 and 30 mm narrower, a 0.62% difference in overall diameter.

With the speedometer calibrated for 265/70R17, an indicated 60 mph is actually 60.4 mph on 235/80R17, and revolutions per mile change from 638 to 634.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 265/70R17

Other comparisons with 235/80R17

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