TireSizesFinder

285/45R21 vs 275/50R21

275/50R21 is 0.73 in (18.5 mm) taller than 285/45R21, a +2.34% diameter difference. With the speedometer set for 285/45R21, an indicated 60 mph is 61.4 mph on 275/50R21.

Is this a safe swap?

Diameter difference +2.34%: within the ±3% guideline

By overall diameter alone, 275/50R21 falls inside the ±3% range commonly used as a guideline when replacing 285/45R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 285/45R21 (31.10 in) vs 275/50R21 (31.83 in)285/45R2131.10 in × 11.22 in275/50R2131.83 in × 10.83 in
Side profile and tread width, drawn to the same scale.
285/45R21 vs 275/50R21 differences
Measurement285/45R21275/50R21Difference% diff
Overall diameter31.10 in (789.9 mm)31.83 in (808.4 mm)+0.73 in (+18.5 mm)+2.34%
Sidewall height5.05 in (128.3 mm)5.41 in (137.5 mm)+0.36 in (+9.3 mm)+7.21%
Section width11.22 in (285.0 mm)10.83 in (275.0 mm)−0.39 in (−10.0 mm)−3.51%
Circumference97.70 in (2,481.5 mm)99.99 in (2,539.7 mm)+2.29 in (+58.1 mm)+2.34%
Revolutions per mile649634−15−2.29%
True speed with the speedometer calibrated for 285/45R21
IndicatedActual on 285/45R21Actual on 275/50R21Difference
30 mph30.0 mph30.7 mph+0.7 mph
60 mph60.0 mph61.4 mph+1.4 mph
75 mph75.0 mph76.8 mph+1.8 mph

Ride-height change: 275/50R21 raises the vehicle by 0.36 in (9.3 mm) at the axle (half the +18.5 mm diameter difference).

275/50R21 is 0.73 in taller than 285/45R21 and 10 mm narrower, a 2.34% difference in overall diameter.

With the speedometer calibrated for 285/45R21, an indicated 60 mph is actually 61.4 mph on 275/50R21, and revolutions per mile change from 649 to 634.

Both sizes mount on 21-inch wheels.

Size pages

Other comparisons with 285/45R21

Other comparisons with 275/50R21

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