325/60R18 in inches

A 325/60R18 tire is 33.4″ tall and 12.8″ wide, and fits a 18″ wheel. In inches it is written 33.4×12.8R18.

Diameter33.35″

Width12.80″

Sidewall7.68″

Drawn to scale. Nominal dimensions calculated from the size code.

Manufacturer data

How tall 325/60R18 tires really are

Heights published by Toyo for the one tire in this size. Their published revolutions per mile work out to 32.4″ under load (below).

The one tire listed, the Toyo Open Country A/T III, measures 33.35″: 0.01″ shorter than the size code's 33.35″.

Height under load32.4″

Published revs per mile (623) mean the tire rolls like a 32.4″ tire on the vehicle. Use this for speedometer calibration.

1 tire in 325/60R18

Sort by the spec you care about.

	Load					Revs/mi	Source
Toyo Open Country A/T IIIAll-terrain	LT E · 124/121S	33.35	66.4	17.0	3,525	623	Spec page

Is 325/60R18 a 33-inch tire?

≈33″

Yes. The size code works out to 33.35″, and the 1 tire here publishes 33.35″, so people call it a 33.

All 33-inch tire sizes, on every wheel size.

A true 33×12.50R18 is 0.35″ shorter on paper and 0.3″ narrower.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

Size	Diameter ″	vs 325/60R18	Difference
245/75R18	32.47	-0.89″	-2.7%
285/65R18	32.59	-0.77″	-2.3%
265/70R18	32.61	-0.75″	-2.2%
235/80R18	32.80	-0.55″	-1.7%
33×12.50R18	33.00	-0.35″	-1.1%
275/70R18	33.16	-0.20″	-0.6%
295/70R17	33.26	-0.09″	-0.3%
305/65R18	33.61	+0.26″	+0.8%
285/70R18	33.71	+0.35″	+1.1%
295/70R18	34.26	+0.91″	+2.7%

How to read 325/60R18

How to read any tire size

How LT325/60R18 124/121S 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.

1LTLight truck

Marks a light truck (LT) tire.

2325Section width

325 mm across the widest point, or 12.80 inches. Every 325 size

360Aspect ratio

A percentage, not a measurement: the sidewall is 60% as tall as the tire is wide, which is 195.0 mm or 7.68 inches.

4RConstruction

Radial construction.

518Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 9.5″ to 11.5″.

6124/121Load index

Each tire carries up to 3,525 lb (1,600 kg) on its own, or 3,195 lb (1,450 kg) each when paired on a dual rear axle.

7SSpeed rating

Rated for up to 112 mph sustained.

ELoad range

Printed separately as "LOAD RANGE E": a 10-ply rating, inflated up to 80 psi (standard load-range table). The load range E tires here carry up to 3,525 lb each, as published.

Specification	Inches	Metric
Overall diameter	33.35	847 mm
Section width	12.80	325 mm
Sidewall height	7.68	195.0 mm
Circumference	104.8	2,662 mm
Revolutions per mile (calculated, unloaded)	604.7	376 per km
Revolutions per mile (published by manufacturers)	623	387 per km
Approved wheel width	9.5–11.5	241–292 mm

Speedometer error after switching to 325/60R18

Your actual speed– mph

Questions about 325/60R18

What is 325/60R18 in inches?

33.35 inches tall, 12.80 inches wide, on a 18-inch wheel. Written in inches, that is roughly 33.4×12.8R18.

What wheel width do I need for 325/60R18?

Manufacturers approve 9.5–11.5″ wide wheels for this size.

How many revolutions per mile does a 325/60R18 make?

Published figures run 623 revolutions per mile. The calculated figure is 604.7, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 325/60R18 than 275/70R18?

0.20 inches taller on paper (33.35″ vs 33.16″), which raises the axle about 0.10″. Your speedometer will read about 0.6% slow.