TireSizesFinder

235/80R17 vs 265/65R18

265/65R18 is 0.24 in (6.1 mm) shorter than 235/80R17, a −0.76% diameter difference. With the speedometer set for 235/80R17, an indicated 60 mph is 59.5 mph on 265/65R18.

Is this a safe swap?

Diameter difference −0.76%: under 1%

By overall diameter alone, 265/65R18 is a near match for 235/80R17; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 235/80R17 (31.80 in) vs 265/65R18 (31.56 in)235/80R1731.80 in × 9.25 in265/65R1831.56 in × 10.43 in
Side profile and tread width, drawn to the same scale.
235/80R17 vs 265/65R18 differences
Measurement235/80R17265/65R18Difference% diff
Overall diameter31.80 in (807.8 mm)31.56 in (801.7 mm)−0.24 in (−6.1 mm)−0.76%
Sidewall height7.40 in (188.0 mm)6.78 in (172.3 mm)−0.62 in (−15.7 mm)−8.38%
Section width9.25 in (235.0 mm)10.43 in (265.0 mm)+1.18 in (+30.0 mm)+12.77%
Circumference99.91 in (2,537.8 mm)99.16 in (2,518.6 mm)−0.75 in (−19.2 mm)−0.76%
Revolutions per mile634639+5+0.76%
True speed with the speedometer calibrated for 235/80R17
IndicatedActual on 235/80R17Actual on 265/65R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 265/65R18 lowers the vehicle by 0.12 in (3.0 mm) at the axle (half the −6.1 mm diameter difference).

265/65R18 is 0.24 in shorter than 235/80R17 and 30 mm wider, a 0.76% difference in overall diameter.

With the speedometer calibrated for 235/80R17, an indicated 60 mph is actually 59.5 mph on 265/65R18, and revolutions per mile change from 634 to 639.

265/65R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 235/80R17.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.