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275/60R20 vs 275/70R18 tire size comparison

275/60R20275/70R18

275/70R18 is 0.2 in (0.50%) taller than 275/60R20, with the same section width. They fit different wheels: 275/60R20 a 20-inch wheel and 275/70R18 an 18-inch wheel.

275/60R20 and 275/70R18 side by side

+0.2 in / +0.50%275/60R20: 33.0 in tall, solid line275/70R18: 33.2 in tall, dashed line275/60R20Width 10.8 in (275 mm)Sidewall 6.5 in (165 mm)275/70R18Width 10.8 in (275 mm)Sidewall 7.6 in (193 mm)
275/60R20 is drawn with a solid line and 275/70R18 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 275/60R20 and 275/70R18, with the difference (275/70R18 minus 275/60R20)
Measurement275/60R20275/70R18DifferenceDifference %
Section width10.8 in (275 mm)10.8 in (275 mm)0.0 in (0 mm)0.00%
Sidewall height6.5 in (165 mm)7.6 in (193 mm)+1.1 in (+28 mm)+16.67%
Wheel (rim) diameter20.0 in (508 mm)18.0 in (457 mm)-2.0 in (-51 mm)-10.00%
Overall diameter33.0 in (838 mm)33.2 in (842 mm)+0.2 in (+4 mm)+0.50%
Circumference103.6 in (2633 mm)104.2 in (2646 mm)+0.6 in (+13 mm)+0.50%
Revolutions per mile611608-3-0.50%

Differences are 275/70R18 minus 275/60R20; percentages are relative to 275/60R20. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 0.50%, 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 275/60R20, the actual speed on 275/70R18 is about 60.3 mph. When it reads 60 mph on a vehicle built for 275/70R18, the actual speed on 275/60R20 is about 59.7 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, 275/60R20 against 275/70R18
Speedometer readsActual on 275/70R18 (built for 275/60R20)Actual on 275/60R20 (built for 275/70R18)
20 mph20.1 mph19.9 mph
30 mph30.2 mph29.9 mph
40 mph40.2 mph39.8 mph
50 mph50.3 mph49.8 mph
60 mph60.3 mph59.7 mph
70 mph70.4 mph69.7 mph
80 mph80.4 mph79.6 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.

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Shop for 275/60R20 or 275/70R18 tires

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Other comparisons with 275/60R20

Side-by-side dimensions and speedometer difference for sizes close to 275/60R20 in overall diameter.

Other comparisons with 275/70R18

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

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