TireSizesFinder

265/35R20 vs 265/40R20

265/40R20 is 1.04 in (26.5 mm) taller than 265/35R20, a +3.82% diameter difference. With the speedometer set for 265/35R20, an indicated 60 mph is 62.3 mph on 265/40R20.

Is this a safe swap?

Diameter difference +3.82%: outside the ±3% guideline

By overall diameter alone, 265/40R20 falls outside the ±3% range commonly used as a guideline when replacing 265/35R20; speedometer and ride-height changes are larger. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/35R20 (27.30 in) vs 265/40R20 (28.35 in)265/35R2027.30 in × 10.43 in265/40R2028.35 in × 10.43 in
Side profile and tread width, drawn to the same scale.
265/35R20 vs 265/40R20 differences
Measurement265/35R20265/40R20Difference% diff
Overall diameter27.30 in (693.5 mm)28.35 in (720.0 mm)+1.04 in (+26.5 mm)+3.82%
Sidewall height3.65 in (92.8 mm)4.17 in (106.0 mm)+0.52 in (+13.3 mm)+14.29%
Section width10.43 in (265.0 mm)10.43 in (265.0 mm)0.00 in (0.0 mm)0.00%
Circumference85.78 in (2,178.7 mm)89.05 in (2,261.9 mm)+3.28 in (+83.3 mm)+3.82%
Revolutions per mile739711−27−3.68%
True speed with the speedometer calibrated for 265/35R20
IndicatedActual on 265/35R20Actual on 265/40R20Difference
30 mph30.0 mph31.1 mph+1.1 mph
60 mph60.0 mph62.3 mph+2.3 mph
75 mph75.0 mph77.9 mph+2.9 mph

Ride-height change: 265/40R20 raises the vehicle by 0.52 in (13.3 mm) at the axle (half the +26.5 mm diameter difference).

265/40R20 is 1.04 in taller than 265/35R20 and the same width, a 3.82% difference in overall diameter.

With the speedometer calibrated for 265/35R20, an indicated 60 mph is actually 62.3 mph on 265/40R20, and revolutions per mile change from 739 to 711.

Both sizes mount on 20-inch wheels.

Size pages

Other comparisons with 265/35R20

Other comparisons with 265/40R20

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