TireSizesFinder

285/45R19 vs 265/40R21

265/40R21 is 0.25 in (6.3 mm) taller than 285/45R19, a +0.85% diameter difference. With the speedometer set for 285/45R19, an indicated 60 mph is 60.5 mph on 265/40R21.

Is this a safe swap?

Diameter difference +0.85%: under 1%

By overall diameter alone, 265/40R21 is a near match for 285/45R19; 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: 285/45R19 (29.10 in) vs 265/40R21 (29.35 in)285/45R1929.10 in × 11.22 in265/40R2129.35 in × 10.43 in
Side profile and tread width, drawn to the same scale.
285/45R19 vs 265/40R21 differences
Measurement285/45R19265/40R21Difference% diff
Overall diameter29.10 in (739.1 mm)29.35 in (745.4 mm)+0.25 in (+6.3 mm)+0.85%
Sidewall height5.05 in (128.3 mm)4.17 in (106.0 mm)−0.88 in (−22.2 mm)−17.35%
Section width11.22 in (285.0 mm)10.43 in (265.0 mm)−0.79 in (−20.0 mm)−7.02%
Circumference91.42 in (2,322.0 mm)92.19 in (2,341.7 mm)+0.78 in (+19.8 mm)+0.85%
Revolutions per mile693687−6−0.85%
True speed with the speedometer calibrated for 285/45R19
IndicatedActual on 285/45R19Actual on 265/40R21Difference
30 mph30.0 mph30.3 mph+0.3 mph
60 mph60.0 mph60.5 mph+0.5 mph
75 mph75.0 mph75.6 mph+0.6 mph

Ride-height change: 265/40R21 raises the vehicle by 0.12 in (3.2 mm) at the axle (half the +6.3 mm diameter difference).

265/40R21 is 0.25 in taller than 285/45R19 and 20 mm narrower, a 0.85% difference in overall diameter.

With the speedometer calibrated for 285/45R19, an indicated 60 mph is actually 60.5 mph on 265/40R21, and revolutions per mile change from 693 to 687.

265/40R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 285/45R19.

Size pages

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