tireheight.com

245/75R18 in inches

A 245/75R18 tire is 32.5″ tall and 9.6″ wide, and fits a 18″ wheel. In inches it is written 32.5×9.6R18.

Diameter32.47″
Width9.65″
Sidewall7.23″
245/75R18 drawn to scale: 32.47 inch diameter, 7.23 inch sidewall, 18 inch wheel, 9.65 inch tread width18″ wheel7.23″32.47″ overall9.65″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 245/75R18 tires really are

Heights published by Michelin for the one tire in this size. Their published revolutions per mile work out to 31.5″ under load (below).

The one tire listed, the Michelin Defender LTX M/S 2, measures 32.48″: 0.01″ taller than the size code's 32.47″.

Height under load31.5″

Published revs per mile (640) mean the tire rolls like a 31.5″ tire on the vehicle. Use this for speedometer calibration.

1 tire in 245/75R18

Sort by the spec you care about.

LoadRevs/miSource
Michelin Defender LTX M/S 2All-seasonXL · 115T32.4836.612.52,679640Spec page

Is 245/75R18 a 32-inch tire?

≈32″

Close. The size code works out to 32.47″, and the 1 tire here publishes 32.48″, so people call it a 32.

All 32-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 245/75R18Difference
255/70R1832.06-0.41″-1.3%
275/65R1832.07-0.39″-1.2%
305/60R1832.41-0.06″-0.2%
285/65R1832.59+0.12″+0.4%
265/70R1832.61+0.14″+0.4%
305/65R1732.61+0.14″+0.4%
235/80R1832.80+0.33″+1.0%
33×12.50R1833.00+0.53″+1.6%
275/70R1833.16+0.69″+2.1%
325/60R1833.35+0.89″+2.7%

How to read 245/75R18

How to read any tire size

245/75R18 115T as printed on the tire sidewall, with each part numbered245/75R18 115T123456
How 245/75R18 115T is printed on the sidewall. It's the most common code among the 1 tire here; tires in this size come in other load and speed ratings too.
1245Section width

245 mm across the widest point, or 9.65 inches. Every 245 size

275Aspect ratio

A percentage, not a measurement: the sidewall is 75% as tall as the tire is wide, which is 183.8 mm or 7.23 inches.

3RConstruction

Radial construction.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 6.5″ to 8.0″.

5115Load index

Each tire carries up to 2,679 lb (1,215 kg) at its maximum pressure.

6TSpeed rating

Rated for up to 118 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter32.47825 mm
Section width9.65245 mm
Sidewall height7.23183.8 mm
Circumference102.02,591 mm
Revolutions per mile (calculated, unloaded)621.2386 per km
Revolutions per mile (published by manufacturers)640398 per km
Approved wheel width6.5–8.0165–203 mm

Speedometer error after switching to 245/75R18

Your actual speed– mph

Questions about 245/75R18

What is 245/75R18 in inches?

32.47 inches tall, 9.65 inches wide, on a 18-inch wheel. Written in inches, that is roughly 32.5×9.6R18.

What wheel width do I need for 245/75R18?

Manufacturers approve 6.5–8.0″ wide wheels for this size.

How many revolutions per mile does a 245/75R18 make?

Published figures run 640 revolutions per mile. The calculated figure is 621.2, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 245/75R18 than 305/60R18?

0.06 inches taller on paper (32.47″ vs 32.41″), which raises the axle about 0.03″. Your speedometer will read about 0.2% slow.