265/50R19 vs 235/45R21

235/45R21 is 0.11 in (2.7 mm) shorter than 265/50R19, a −0.36% diameter difference. With the speedometer set for 265/50R19, an indicated 60 mph is 59.8 mph on 235/45R21.

Is this a safe swap?

Diameter difference −0.36%: under 1%

By overall diameter alone, 235/45R21 is a near match for 265/50R19; 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: 265/50R19 (29.43 in) vs 235/45R21 (29.33 in)265/50R1929.43 in × 10.43 in235/45R2129.33 in × 9.25 in
Side profile and tread width, drawn to the same scale.
265/50R19 vs 235/45R21 differences
Measurement265/50R19235/45R21Difference% diff
Overall diameter29.43 in (747.6 mm)29.33 in (744.9 mm)−0.11 in (−2.7 mm)−0.36%
Sidewall height5.22 in (132.5 mm)4.16 in (105.8 mm)−1.05 in (−26.7 mm)−20.19%
Section width10.43 in (265.0 mm)9.25 in (235.0 mm)−1.18 in (−30.0 mm)−11.32%
Circumference92.47 in (2,348.7 mm)92.13 in (2,340.2 mm)−0.33 in (−8.5 mm)−0.36%
Revolutions per mile685688+2+0.36%
True speed with the speedometer calibrated for 265/50R19
IndicatedActual on 265/50R19Actual on 235/45R21Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.8 mph−0.2 mph
75 mph75.0 mph74.7 mph−0.3 mph

Ride-height change: 235/45R21 lowers the vehicle by 0.05 in (1.3 mm) at the axle (half the −2.7 mm diameter difference).

235/45R21 is 0.11 in shorter than 265/50R19 and 30 mm narrower, a 0.36% difference in overall diameter.

With the speedometer calibrated for 265/50R19, an indicated 60 mph is actually 59.8 mph on 235/45R21, and revolutions per mile change from 685 to 688.

235/45R21 mounts on a 21-inch wheel, a plus-2 fitment from the 19-inch wheel of 265/50R19.

Size pages

Other comparisons with 265/50R19

Other comparisons with 235/45R21

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