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275/70R18 vs 33x12.50R15 tire size comparison

275/70R1833x12.50R15

33x12.50R15 is 0.2 in (0.47%) shorter than 275/70R18 and 1.7 in wider. They fit different wheels: 275/70R18 an 18-inch wheel and 33x12.50R15 a 15-inch wheel.

275/70R18 and 33x12.50R15 side by side

-0.2 in / -0.47%275/70R18: 33.2 in tall, solid line33x12.50R15: 33.0 in tall, dashed line275/70R18Width 10.8 in (275 mm)Sidewall 7.6 in (193 mm)33x12.50R15Width 12.5 in (318 mm)Sidewall 9.0 in (229 mm)
275/70R18 is drawn with a solid line and 33x12.50R15 with a dashed line. In each drawing both tires are to the same scale; the tread shoulder and bead curves are simplified. The table below has the same numbers.
Dimensions of 275/70R18 and 33x12.50R15, with the difference (33x12.50R15 minus 275/70R18)
Measurement275/70R1833x12.50R15DifferenceDifference %
Section width10.8 in (275 mm)12.5 in (318 mm)+1.7 in (+43 mm)+15.45%
Sidewall height7.6 in (193 mm)9.0 in (229 mm)+1.4 in (+36 mm)+18.75%
Wheel (rim) diameter18.0 in (457 mm)15.0 in (381 mm)-3.0 in (-76 mm)-16.67%
Overall diameter33.2 in (842 mm)33.0 in (838 mm)-0.2 in (-4 mm)-0.47%
Circumference104.2 in (2646 mm)103.7 in (2633 mm)-0.5 in (-13 mm)-0.47%
Revolutions per mile608611+3+0.48%

Differences are 33x12.50R15 minus 275/70R18; percentages are relative to 275/70R18. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 0.47%, which is within the common 3% rule of thumb.

The rule of thumb keeps a replacement size within about 3% of the original overall diameter. It covers diameter only. It is not a fit, load or safety check, because width, wheel diameter, load capacity and clearance matter too. Confirm any size change with your vehicle's owner's manual or a tire professional.

Speedometer difference

When the speedometer reads 60 mph on a vehicle built for 275/70R18, the actual speed on 33x12.50R15 is about 59.7 mph. When it reads 60 mph on a vehicle built for 33x12.50R15, the actual speed on 275/70R18 is about 60.3 mph. These figures assume the speedometer is accurate on the original size and use nominal dimensions, so treat them as estimates.

Actual speed for a given speedometer reading, 275/70R18 against 33x12.50R15
Speedometer readsActual on 33x12.50R15 (built for 275/70R18)Actual on 275/70R18 (built for 33x12.50R15)
20 mph19.9 mph20.1 mph
30 mph29.9 mph30.1 mph
40 mph39.8 mph40.2 mph
50 mph49.8 mph50.2 mph
60 mph59.7 mph60.3 mph
70 mph69.7 mph70.3 mph
80 mph79.6 mph80.4 mph

A common rule of thumb is to keep a replacement size within about 3% of the original overall diameter. Check the tire placard on the driver's door jamb and your owner's manual for the sizes your vehicle was built for. Confirm any size change with your vehicle's owner's manual or a tire professional.

Which vehicles use each size?

These vehicles list the size among their verified sizes, by trim. Open one to see all of its sizes.

Check it in the calculator

The calculator takes the same two sizes and shows the full comparison, or lets you swap either one for another size.

Open this comparison in the calculator

Shop for 275/70R18 or 33x12.50R15 tires

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Other comparisons with 275/70R18

Side-by-side dimensions and speedometer difference for sizes close to 275/70R18 in overall diameter.

Other comparisons with 33x12.50R15

Side-by-side dimensions and speedometer difference for sizes close to 33x12.50R15 in overall diameter.

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