TireSizesFinder

245/45R21 vs 315/30R22

315/30R22 is 0.24 in (6.1 mm) shorter than 245/45R21, a −0.81% diameter difference. With the speedometer set for 245/45R21, an indicated 60 mph is 59.5 mph on 315/30R22.

Is this a safe swap?

Diameter difference −0.81%: under 1%

By overall diameter alone, 315/30R22 is a near match for 245/45R21; 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: 245/45R21 (29.68 in) vs 315/30R22 (29.44 in)245/45R2129.68 in × 9.65 in315/30R2229.44 in × 12.40 in
Side profile and tread width, drawn to the same scale.
245/45R21 vs 315/30R22 differences
Measurement245/45R21315/30R22Difference% diff
Overall diameter29.68 in (753.9 mm)29.44 in (747.8 mm)−0.24 in (−6.1 mm)−0.81%
Sidewall height4.34 in (110.3 mm)3.72 in (94.5 mm)−0.62 in (−15.7 mm)−14.29%
Section width9.65 in (245.0 mm)12.40 in (315.0 mm)+2.76 in (+70.0 mm)+28.57%
Circumference93.25 in (2,368.4 mm)92.49 in (2,349.3 mm)−0.75 in (−19.2 mm)−0.81%
Revolutions per mile679685+6+0.82%
True speed with the speedometer calibrated for 245/45R21
IndicatedActual on 245/45R21Actual on 315/30R22Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.5 mph−0.5 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 315/30R22 lowers the vehicle by 0.12 in (3.1 mm) at the axle (half the −6.1 mm diameter difference).

315/30R22 is 0.24 in shorter than 245/45R21 and 70 mm wider, a 0.81% difference in overall diameter.

With the speedometer calibrated for 245/45R21, an indicated 60 mph is actually 59.5 mph on 315/30R22, and revolutions per mile change from 679 to 685.

315/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 245/45R21.

Size pages

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