TireSizesFinder

225/60R16 vs 265/40R18

265/40R18 is 0.28 in (7.2 mm) shorter than 225/60R16, a −1.06% diameter difference. With the speedometer set for 225/60R16, an indicated 60 mph is 59.4 mph on 265/40R18.

Is this a safe swap?

Diameter difference −1.06%: within the ±3% guideline

By overall diameter alone, 265/40R18 falls inside the ±3% range commonly used as a guideline when replacing 225/60R16. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 225/60R16 (26.63 in) vs 265/40R18 (26.35 in)225/60R1626.63 in × 8.86 in265/40R1826.35 in × 10.43 in
Side profile and tread width, drawn to the same scale.
225/60R16 vs 265/40R18 differences
Measurement225/60R16265/40R18Difference% diff
Overall diameter26.63 in (676.4 mm)26.35 in (669.2 mm)−0.28 in (−7.2 mm)−1.06%
Sidewall height5.31 in (135.0 mm)4.17 in (106.0 mm)−1.14 in (−29.0 mm)−21.48%
Section width8.86 in (225.0 mm)10.43 in (265.0 mm)+1.57 in (+40.0 mm)+17.78%
Circumference83.66 in (2,125.0 mm)82.77 in (2,102.4 mm)−0.89 in (−22.6 mm)−1.06%
Revolutions per mile757765+8+1.08%
True speed with the speedometer calibrated for 225/60R16
IndicatedActual on 225/60R16Actual on 265/40R18Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.4 mph−0.6 mph
75 mph75.0 mph74.2 mph−0.8 mph

Ride-height change: 265/40R18 lowers the vehicle by 0.14 in (3.6 mm) at the axle (half the −7.2 mm diameter difference).

265/40R18 is 0.28 in shorter than 225/60R16 and 40 mm wider, a 1.06% difference in overall diameter.

With the speedometer calibrated for 225/60R16, an indicated 60 mph is actually 59.4 mph on 265/40R18, and revolutions per mile change from 757 to 765.

265/40R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/60R16.

Size pages

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