295/35R21 vs 315/30R22

315/30R22 is 0.31 in (7.9 mm) taller than 295/35R21, a +1.07% diameter difference. With the speedometer set for 295/35R21, an indicated 60 mph is 60.6 mph on 315/30R22.

Is this a safe swap?

Diameter difference +1.07%: within the ±3% guideline

By overall diameter alone, 315/30R22 falls inside the ±3% range commonly used as a guideline when replacing 295/35R21. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

295/35R21 vs 315/30R22 differences
Measurement	295/35R21	315/30R22	Difference	% diff
Overall diameter	29.13 in (739.9 mm)	29.44 in (747.8 mm)	+0.31 in (+7.9 mm)	+1.07%
Sidewall height	4.06 in (103.3 mm)	3.72 in (94.5 mm)	−0.34 in (−8.7 mm)	−8.47%
Section width	11.61 in (295.0 mm)	12.40 in (315.0 mm)	+0.79 in (+20.0 mm)	+6.78%
Circumference	91.51 in (2,324.5 mm)	92.49 in (2,349.3 mm)	+0.98 in (+24.8 mm)	+1.07%
Revolutions per mile	692	685	−7	−1.06%

True speed with the speedometer calibrated for 295/35R21
Indicated	Actual on 295/35R21	Actual on 315/30R22	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.8 mph	+0.8 mph

Ride-height change: 315/30R22 raises the vehicle by 0.16 in (3.9 mm) at the axle (half the +7.9 mm diameter difference).

315/30R22 is 0.31 in taller than 295/35R21 and 20 mm wider, a 1.07% difference in overall diameter.

With the speedometer calibrated for 295/35R21, an indicated 60 mph is actually 60.6 mph on 315/30R22, and revolutions per mile change from 692 to 685.

315/30R22 mounts on a 22-inch wheel, a plus-1 fitment from the 21-inch wheel of 295/35R21.

Size pages

Other comparisons with 295/35R21

Other comparisons with 315/30R22

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.