TireSizesFinder

265/70R15 vs 30x9.50R15

30x9.50R15 is 0.39 in (10.0 mm) taller than 265/70R15, a +1.33% diameter difference. With the speedometer set for 265/70R15, an indicated 60 mph is 60.8 mph on 30x9.50R15.

Is this a safe swap?

Diameter difference +1.33%: within the ±3% guideline

By overall diameter alone, 30x9.50R15 falls inside the ±3% range commonly used as a guideline when replacing 265/70R15. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 265/70R15 (29.61 in) vs 30x9.50R15 (30.00 in)265/70R1529.61 in × 10.43 in30x9.50R1530.00 in × 9.50 in
Side profile and tread width, drawn to the same scale.
265/70R15 vs 30x9.50R15 differences
Measurement265/70R1530x9.50R15Difference% diff
Overall diameter29.61 in (752.0 mm)30.00 in (762.0 mm)+0.39 in (+10.0 mm)+1.33%
Sidewall height7.30 in (185.5 mm)7.50 in (190.5 mm)+0.20 in (+5.0 mm)+2.70%
Section width10.43 in (265.0 mm)9.50 in (241.3 mm)−0.93 in (−23.7 mm)−8.94%
Circumference93.01 in (2,362.5 mm)94.25 in (2,393.9 mm)+1.24 in (+31.4 mm)+1.33%
Revolutions per mile681672−9−1.31%
True speed with the speedometer calibrated for 265/70R15
IndicatedActual on 265/70R15Actual on 30x9.50R15Difference
30 mph30.0 mph30.4 mph+0.4 mph
60 mph60.0 mph60.8 mph+0.8 mph
75 mph75.0 mph76.0 mph+1.0 mph

Ride-height change: 30x9.50R15 raises the vehicle by 0.20 in (5.0 mm) at the axle (half the +10.0 mm diameter difference).

30x9.50R15 is 0.39 in taller than 265/70R15 and 24 mm narrower, a 1.33% difference in overall diameter.

With the speedometer calibrated for 265/70R15, an indicated 60 mph is actually 60.8 mph on 30x9.50R15, and revolutions per mile change from 681 to 672.

Both sizes mount on 15-inch wheels.

Size pages

Other comparisons with 265/70R15

Other comparisons with 30x9.50R15

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