TireSizesFinder

295/40R19 vs 255/35R21

255/35R21 is 0.26 in (6.7 mm) shorter than 295/40R19, a −0.93% diameter difference. With the speedometer set for 295/40R19, an indicated 60 mph is 59.4 mph on 255/35R21.

Is this a safe swap?

Diameter difference −0.93%: under 1%

By overall diameter alone, 255/35R21 is a near match for 295/40R19; 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: 295/40R19 (28.29 in) vs 255/35R21 (28.03 in)295/40R1928.29 in × 11.61 in255/35R2128.03 in × 10.04 in
Side profile and tread width, drawn to the same scale.
295/40R19 vs 255/35R21 differences
Measurement295/40R19255/35R21Difference% diff
Overall diameter28.29 in (718.6 mm)28.03 in (711.9 mm)−0.26 in (−6.7 mm)−0.93%
Sidewall height4.65 in (118.0 mm)3.51 in (89.3 mm)−1.13 in (−28.7 mm)−24.36%
Section width11.61 in (295.0 mm)10.04 in (255.0 mm)−1.57 in (−40.0 mm)−13.56%
Circumference88.88 in (2,257.5 mm)88.05 in (2,236.5 mm)−0.83 in (−21.0 mm)−0.93%
Revolutions per mile713720+7+0.94%
True speed with the speedometer calibrated for 295/40R19
IndicatedActual on 295/40R19Actual on 255/35R21Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.4 mph−0.6 mph
75 mph75.0 mph74.3 mph−0.7 mph

Ride-height change: 255/35R21 lowers the vehicle by 0.13 in (3.3 mm) at the axle (half the −6.7 mm diameter difference).

255/35R21 is 0.26 in shorter than 295/40R19 and 40 mm narrower, a 0.93% difference in overall diameter.

With the speedometer calibrated for 295/40R19, an indicated 60 mph is actually 59.4 mph on 255/35R21, and revolutions per mile change from 713 to 720.

255/35R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 295/40R19.

Size pages

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