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LT255/75R17 vs LT265/70R18 tire size comparison

LT255/75R17LT265/70R18

LT265/70R18 is 0.5 in (1.71%) taller than LT255/75R17 and 0.4 in wider. They fit different wheels: LT255/75R17 a 17-inch wheel and LT265/70R18 an 18-inch wheel.

LT255/75R17 and LT265/70R18 side by side

+0.5 in / +1.71%LT255/75R17: 32.1 in tall, solid lineLT265/70R18: 32.6 in tall, dashed lineLT255/75R17Width 10.0 in (255 mm)Sidewall 7.5 in (191 mm)LT265/70R18Width 10.4 in (265 mm)Sidewall 7.3 in (186 mm)
LT255/75R17 is drawn with a solid line and LT265/70R18 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 LT255/75R17 and LT265/70R18, with the difference (LT265/70R18 minus LT255/75R17)
MeasurementLT255/75R17LT265/70R18DifferenceDifference %
Section width10.0 in (255 mm)10.4 in (265 mm)+0.4 in (+10 mm)+3.92%
Sidewall height7.5 in (191 mm)7.3 in (186 mm)-0.2 in (-5 mm)-3.01%
Wheel (rim) diameter17.0 in (432 mm)18.0 in (457 mm)+1.0 in (+25 mm)+5.88%
Overall diameter32.1 in (814 mm)32.6 in (828 mm)+0.5 in (+14 mm)+1.71%
Circumference100.7 in (2558 mm)102.4 in (2602 mm)+1.7 in (+44 mm)+1.71%
Revolutions per mile629619-10-1.68%

Differences are LT265/70R18 minus LT255/75R17; percentages are relative to LT255/75R17. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 1.71%, 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 LT255/75R17, the actual speed on LT265/70R18 is about 61.0 mph. When it reads 60 mph on a vehicle built for LT265/70R18, the actual speed on LT255/75R17 is about 59.0 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, LT255/75R17 against LT265/70R18
Speedometer readsActual on LT265/70R18 (built for LT255/75R17)Actual on LT255/75R17 (built for LT265/70R18)
20 mph20.3 mph19.7 mph
30 mph30.5 mph29.5 mph
40 mph40.7 mph39.3 mph
50 mph50.9 mph49.2 mph
60 mph61.0 mph59.0 mph
70 mph71.2 mph68.8 mph
80 mph81.4 mph78.7 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 LT255/75R17 or LT265/70R18 tires

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Other comparisons with LT255/75R17

Side-by-side dimensions and speedometer difference for sizes close to LT255/75R17 in overall diameter.

Other comparisons with LT265/70R18

Side-by-side dimensions and speedometer difference for sizes close to LT265/70R18 in overall diameter.

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