TireSizesFinder

275/50R19 vs 275/40R21

275/40R21 is 0.17 in (4.2 mm) shorter than 275/50R19, a −0.55% diameter difference. With the speedometer set for 275/50R19, an indicated 60 mph is 59.7 mph on 275/40R21.

Is this a safe swap?

Diameter difference −0.55%: under 1%

By overall diameter alone, 275/40R21 is a near match for 275/50R19; 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: 275/50R19 (29.83 in) vs 275/40R21 (29.66 in)275/50R1929.83 in × 10.83 in275/40R2129.66 in × 10.83 in
Side profile and tread width, drawn to the same scale.
275/50R19 vs 275/40R21 differences
Measurement275/50R19275/40R21Difference% diff
Overall diameter29.83 in (757.6 mm)29.66 in (753.4 mm)−0.17 in (−4.2 mm)−0.55%
Sidewall height5.41 in (137.5 mm)4.33 in (110.0 mm)−1.08 in (−27.5 mm)−20.00%
Section width10.83 in (275.0 mm)10.83 in (275.0 mm)0.00 in (0.0 mm)0.00%
Circumference93.70 in (2,380.1 mm)93.18 in (2,366.9 mm)−0.52 in (−13.2 mm)−0.55%
Revolutions per mile676680+4+0.56%
True speed with the speedometer calibrated for 275/50R19
IndicatedActual on 275/50R19Actual on 275/40R21Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.7 mph−0.3 mph
75 mph75.0 mph74.6 mph−0.4 mph

Ride-height change: 275/40R21 lowers the vehicle by 0.08 in (2.1 mm) at the axle (half the −4.2 mm diameter difference).

275/40R21 is 0.17 in shorter than 275/50R19 and the same width, a 0.55% difference in overall diameter.

With the speedometer calibrated for 275/50R19, an indicated 60 mph is actually 59.7 mph on 275/40R21, and revolutions per mile change from 676 to 680.

275/40R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 275/50R19.

Size pages

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