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LT275/65R18 vs LT275/70R17 tire size comparison

LT275/65R18LT275/70R17

LT275/70R17 is 0.1 in (0.26%) taller than LT275/65R18, with the same section width. They fit different wheels: LT275/65R18 an 18-inch wheel and LT275/70R17 a 17-inch wheel.

LT275/65R18 and LT275/70R17 side by side

+0.1 in / +0.26%LT275/65R18: 32.1 in tall, solid lineLT275/70R17: 32.2 in tall, dashed lineLT275/65R18Width 10.8 in (275 mm)Sidewall 7.0 in (179 mm)LT275/70R17Width 10.8 in (275 mm)Sidewall 7.6 in (193 mm)
LT275/65R18 is drawn with a solid line and LT275/70R17 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 LT275/65R18 and LT275/70R17, with the difference (LT275/70R17 minus LT275/65R18)
MeasurementLT275/65R18LT275/70R17DifferenceDifference %
Section width10.8 in (275 mm)10.8 in (275 mm)0.0 in (0 mm)0.00%
Sidewall height7.0 in (179 mm)7.6 in (193 mm)+0.6 in (+14 mm)+7.69%
Wheel (rim) diameter18.0 in (457 mm)17.0 in (432 mm)-1.0 in (-25 mm)-5.56%
Overall diameter32.1 in (815 mm)32.2 in (817 mm)+0.1 in (+2 mm)+0.26%
Circumference100.8 in (2559 mm)101.0 in (2566 mm)+0.2 in (+7 mm)+0.26%
Revolutions per mile629627-2-0.26%

Differences are LT275/70R17 minus LT275/65R18; percentages are relative to LT275/65R18. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 0.26%, 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 LT275/65R18, the actual speed on LT275/70R17 is about 60.2 mph. When it reads 60 mph on a vehicle built for LT275/70R17, the actual speed on LT275/65R18 is about 59.8 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, LT275/65R18 against LT275/70R17
Speedometer readsActual on LT275/70R17 (built for LT275/65R18)Actual on LT275/65R18 (built for LT275/70R17)
20 mph20.1 mph19.9 mph
30 mph30.1 mph29.9 mph
40 mph40.1 mph39.9 mph
50 mph50.1 mph49.9 mph
60 mph60.2 mph59.8 mph
70 mph70.2 mph69.8 mph
80 mph80.2 mph79.8 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 LT275/65R18 or LT275/70R17 tires

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Other comparisons with LT275/65R18

Side-by-side dimensions and speedometer difference for sizes close to LT275/65R18 in overall diameter.

Other comparisons with LT275/70R17

Side-by-side dimensions and speedometer difference for sizes close to LT275/70R17 in overall diameter.

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