TireSizesFinder

305/30R19 vs 265/30R20

265/30R20 is 0.06 in (1.4 mm) taller than 305/30R19, a +0.21% diameter difference. With the speedometer set for 305/30R19, an indicated 60 mph is 60.1 mph on 265/30R20.

Is this a safe swap?

Diameter difference +0.21%: under 1%

By overall diameter alone, 265/30R20 is a near match for 305/30R19; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 305/30R19 (26.20 in) vs 265/30R20 (26.26 in)305/30R1926.20 in × 12.01 in265/30R2026.26 in × 10.43 in
Side profile and tread width, drawn to the same scale.
305/30R19 vs 265/30R20 differences
Measurement305/30R19265/30R20Difference% diff
Overall diameter26.20 in (665.6 mm)26.26 in (667.0 mm)+0.06 in (+1.4 mm)+0.21%
Sidewall height3.60 in (91.5 mm)3.13 in (79.5 mm)−0.47 in (−12.0 mm)−13.11%
Section width12.01 in (305.0 mm)10.43 in (265.0 mm)−1.57 in (−40.0 mm)−13.11%
Circumference82.32 in (2,091.0 mm)82.50 in (2,095.4 mm)+0.17 in (+4.4 mm)+0.21%
Revolutions per mile770768−2−0.21%
True speed with the speedometer calibrated for 305/30R19
IndicatedActual on 305/30R19Actual on 265/30R20Difference
30 mph30.0 mph30.1 mph+0.1 mph
60 mph60.0 mph60.1 mph+0.1 mph
75 mph75.0 mph75.2 mph+0.2 mph

Ride-height change: 265/30R20 raises the vehicle by 0.03 in (0.7 mm) at the axle (half the +1.4 mm diameter difference).

265/30R20 is 0.06 in taller than 305/30R19 and 40 mm narrower, a 0.21% difference in overall diameter.

With the speedometer calibrated for 305/30R19, an indicated 60 mph is actually 60.1 mph on 265/30R20, and revolutions per mile change from 770 to 768.

265/30R20 mounts on a 20-inch wheel, a plus-1 fitment from the 19-inch wheel of 305/30R19.

Size pages

Other comparisons with 305/30R19

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