255/40R22 vs 305/35R22

305/35R22 is 0.37 in (9.5 mm) taller than 255/40R22, a +1.25% diameter difference. With the speedometer set for 255/40R22, an indicated 60 mph is 60.7 mph on 305/35R22.

Is this a safe swap?

Diameter difference +1.25%: within the ±3% guideline

By overall diameter alone, 305/35R22 falls inside the ±3% range commonly used as a guideline when replacing 255/40R22. 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.

255/40R22 vs 305/35R22 differences
Measurement	255/40R22	305/35R22	Difference	% diff
Overall diameter	30.03 in (762.8 mm)	30.41 in (772.3 mm)	+0.37 in (+9.5 mm)	+1.25%
Sidewall height	4.02 in (102.0 mm)	4.20 in (106.8 mm)	+0.19 in (+4.8 mm)	+4.66%
Section width	10.04 in (255.0 mm)	12.01 in (305.0 mm)	+1.97 in (+50.0 mm)	+19.61%
Circumference	94.35 in (2,396.4 mm)	95.52 in (2,426.3 mm)	+1.18 in (+29.8 mm)	+1.25%
Revolutions per mile	672	663	−8	−1.23%

True speed with the speedometer calibrated for 255/40R22
Indicated	Actual on 255/40R22	Actual on 305/35R22	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 305/35R22 raises the vehicle by 0.19 in (4.8 mm) at the axle (half the +9.5 mm diameter difference).

305/35R22 is 0.37 in taller than 255/40R22 and 50 mm wider, a 1.25% difference in overall diameter.

With the speedometer calibrated for 255/40R22, an indicated 60 mph is actually 60.7 mph on 305/35R22, and revolutions per mile change from 672 to 663.

Both sizes mount on 22-inch wheels.

Size pages

Other comparisons with 255/40R22

Other comparisons with 305/35R22

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