TireSizesFinder

235/55R19 vs 265/40R21

265/40R21 is 0.17 in (4.3 mm) taller than 235/55R19, a +0.58% diameter difference. With the speedometer set for 235/55R19, an indicated 60 mph is 60.3 mph on 265/40R21.

Is this a safe swap?

Diameter difference +0.58%: under 1%

By overall diameter alone, 265/40R21 is a near match for 235/55R19; 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: 235/55R19 (29.18 in) vs 265/40R21 (29.35 in)235/55R1929.18 in × 9.25 in265/40R2129.35 in × 10.43 in
Side profile and tread width, drawn to the same scale.
235/55R19 vs 265/40R21 differences
Measurement235/55R19265/40R21Difference% diff
Overall diameter29.18 in (741.1 mm)29.35 in (745.4 mm)+0.17 in (+4.3 mm)+0.58%
Sidewall height5.09 in (129.3 mm)4.17 in (106.0 mm)−0.92 in (−23.2 mm)−17.99%
Section width9.25 in (235.0 mm)10.43 in (265.0 mm)+1.18 in (+30.0 mm)+12.77%
Circumference91.66 in (2,328.2 mm)92.19 in (2,341.7 mm)+0.53 in (+13.5 mm)+0.58%
Revolutions per mile691687−4−0.58%
True speed with the speedometer calibrated for 235/55R19
IndicatedActual on 235/55R19Actual on 265/40R21Difference
30 mph30.0 mph30.2 mph+0.2 mph
60 mph60.0 mph60.3 mph+0.3 mph
75 mph75.0 mph75.4 mph+0.4 mph

Ride-height change: 265/40R21 raises the vehicle by 0.08 in (2.2 mm) at the axle (half the +4.3 mm diameter difference).

265/40R21 is 0.17 in taller than 235/55R19 and 30 mm wider, a 0.58% difference in overall diameter.

With the speedometer calibrated for 235/55R19, an indicated 60 mph is actually 60.3 mph on 265/40R21, and revolutions per mile change from 691 to 687.

265/40R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 235/55R19.

Size pages

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