295/35R19 vs 295/30R20

295/30R20 is 0.16 in (4.1 mm) shorter than 295/35R19, a −0.59% diameter difference. With the speedometer set for 295/35R19, an indicated 60 mph is 59.6 mph on 295/30R20.

Is this a safe swap?

Diameter difference −0.59%: under 1%

By overall diameter alone, 295/30R20 is a near match for 295/35R19; the speedometer changes by less than 1%. 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.

295/35R19 vs 295/30R20 differences
Measurement	295/35R19	295/30R20	Difference	% diff
Overall diameter	27.13 in (689.1 mm)	26.97 in (685.0 mm)	−0.16 in (−4.1 mm)	−0.59%
Sidewall height	4.06 in (103.3 mm)	3.48 in (88.5 mm)	−0.58 in (−14.7 mm)	−14.29%
Section width	11.61 in (295.0 mm)	11.61 in (295.0 mm)	0.00 in (0.0 mm)	0.00%
Circumference	85.23 in (2,164.9 mm)	84.72 in (2,152.0 mm)	−0.51 in (−12.9 mm)	−0.59%
Revolutions per mile	743	748	+4	+0.60%

True speed with the speedometer calibrated for 295/35R19
Indicated	Actual on 295/35R19	Actual on 295/30R20	Difference
30 mph	30.0 mph	29.8 mph	−0.2 mph
60 mph	60.0 mph	59.6 mph	−0.4 mph
75 mph	75.0 mph	74.6 mph	−0.4 mph

Ride-height change: 295/30R20 lowers the vehicle by 0.08 in (2.0 mm) at the axle (half the −4.1 mm diameter difference).

295/30R20 is 0.16 in shorter than 295/35R19 and the same width, a 0.59% difference in overall diameter.

With the speedometer calibrated for 295/35R19, an indicated 60 mph is actually 59.6 mph on 295/30R20, and revolutions per mile change from 743 to 748.

295/30R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 295/35R19.

Size pages

Other comparisons with 295/35R19

Other comparisons with 295/30R20

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