35x12.50R20 vs 325/60R20

325/60R20 is 0.35 in (9.0 mm) taller than 35x12.50R20, a +1.01% diameter difference. With the speedometer set for 35x12.50R20, an indicated 60 mph is 60.6 mph on 325/60R20.

Is this a safe swap?

Diameter difference +1.01%: within the ±3% guideline

By overall diameter alone, 325/60R20 falls inside the ±3% range commonly used as a guideline when replacing 35x12.50R20. 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.

35x12.50R20 vs 325/60R20 differences
Measurement	35x12.50R20	325/60R20	Difference	% diff
Overall diameter	35.00 in (889.0 mm)	35.35 in (898.0 mm)	+0.35 in (+9.0 mm)	+1.01%
Sidewall height	7.50 in (190.5 mm)	7.68 in (195.0 mm)	+0.18 in (+4.5 mm)	+2.36%
Section width	12.50 in (317.5 mm)	12.80 in (325.0 mm)	+0.30 in (+7.5 mm)	+2.36%
Circumference	109.96 in (2,792.9 mm)	111.07 in (2,821.2 mm)	+1.11 in (+28.3 mm)	+1.01%
Revolutions per mile	576	570	−6	−1.00%

True speed with the speedometer calibrated for 35x12.50R20
Indicated	Actual on 35x12.50R20	Actual on 325/60R20	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: 325/60R20 raises the vehicle by 0.18 in (4.5 mm) at the axle (half the +9.0 mm diameter difference).

325/60R20 is 0.35 in taller than 35x12.50R20 and 8 mm wider, a 1.01% difference in overall diameter.

With the speedometer calibrated for 35x12.50R20, an indicated 60 mph is actually 60.6 mph on 325/60R20, and revolutions per mile change from 576 to 570.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 35x12.50R20

Other comparisons with 325/60R20

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