255/70R18 in inches

A 255/70R18 tire is 32.1″ tall and 10.0″ wide, and fits a 18″ wheel. In inches it is written 32.1×10.0R18.

Diameter32.06″

Width10.04″

Sidewall7.03″

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

Manufacturer data

How tall 255/70R18 tires really are

Heights published by BFGoodrich, General, Michelin and Toyo for all 14 tires in this size. Their published revolutions per mile work out to 31.1–31.2″ under load (below).

Real 255/70R18 tires measure 32.09–32.30″, against 32.06″ from the size code. Every one runs taller than the size code.

Michelin Latitude Tour HP32.30″ +0.24″
BFGoodrich All-Terrain T/A KO232.10″ +0.04″
BFGoodrich All-Terrain T/A KO332.10″ +0.04″
BFGoodrich Trail-Terrain T/A32.10″ +0.04″
BFGoodrich Trail-Terrain T/A+32.10″ +0.04″
General Grabber A/TSport-W32.10″ +0.04″
General Grabber A/TX32.10″ +0.04″
General Grabber APT32.10″ +0.04″
General Grabber H/T32.10″ +0.04″
Michelin Defender LTX M/S 232.10″ +0.04″
BFGoodrich Advantage Control HT32.09″ +0.03″
Michelin X-Ice Snow32.09″ +0.03″
Toyo Open Country A/T III32.09″ +0.03″
Toyo Open Country H/T II32.09″ +0.03″

Each bar runs from the size code's 32.06″ (the orange line) to the model's published height. The track spans 1.0″. Where a model comes in several load ranges, the darker part shows its range of heights; the number after the name is how many versions it comes in.

Height under load31.1–31.2″

Published revs per mile (647–648) mean the tire rolls like a 31.1–31.2″ tire on the vehicle. Use this for speedometer calibration.

Weight spread35.3–52.3 lb

The lightest (Michelin Latitude Tour HP, XL) is 17.0 lb lighter per corner than the heaviest (BFGoodrich All-Terrain T/A KO3, LT D).

14 tires in 255/70R18

Sort by the spec you care about.

	Load					Revs/mi	Source
Michelin Latitude Tour HPAll-season	XL · 116V	32.30	35.3	9.0	2,505	648	Spec page
Michelin X-Ice SnowWinter	XL · 116T	32.09	36.0	10.5	2,756	648	Spec page
General Grabber A/TSport-WAll-terrain	SL · 113T	32.10	37.5	12.0	2,535	648	Spec page
Michelin Defender LTX M/S 2All-season	XL · 116T	32.10	37.9	12.5	2,756	648	Spec page
General Grabber H/THighway	SL · 113T	32.10	38.4	12.0	2,535	648	Spec page
BFGoodrich Advantage Control HTHighway	SL · 113T	32.09	39.1	12.0	2,535	648	Spec page
Toyo Open Country A/T IIIAll-terrain	SL · 113T	32.09	39.3	13.2	2,535	647	Spec page
General Grabber APTAll-terrain	SL · 113T	32.10	40.0	14.0	2,535	648	Spec page
Toyo Open Country H/T IIHighway	SL · 113S	32.09	41.0	12.0	2,535	647	Spec page
BFGoodrich Trail-Terrain T/AAll-terrain	XL · 116H	32.10	42.8	12.5	2,756	648	Spec page
General Grabber A/TXAll-terrain	SL · 113T	32.10	43.3	14.0	2,535	648	Spec page
BFGoodrich Trail-Terrain T/A+	XL · 116H	32.10	44.1	12.5	2,756	648	Spec page
BFGoodrich All-Terrain T/A KO2All-terrain	LT D · 117S	32.10	50.9	15.0	2,835	648	Spec page
BFGoodrich All-Terrain T/A KO3All-terrain	LT D · 117S	32.10	52.3	15.0	2,835	648	Spec page

Is 255/70R18 a 32-inch tire?

≈32″

Yes. The size code works out to 32.06″, and the 14 tires here publish 32.09–32.30″, 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.

Size	Diameter ″	vs 255/70R18	Difference
285/60R18	31.46	-0.59″	-1.8%
245/70R18	31.50	-0.55″	-1.7%
265/65R18	31.56	-0.49″	-1.5%
255/75R17	32.06	+0.00″	+0.0%
275/65R18	32.07	+0.02″	+0.1%
305/60R18	32.41	+0.35″	+1.1%
245/75R18	32.47	+0.41″	+1.3%
285/65R18	32.59	+0.53″	+1.7%
265/70R18	32.61	+0.55″	+1.7%
235/80R18	32.80	+0.75″	+2.3%

How to read 255/70R18

How to read any tire size

How 255/70R18 113T is printed on the sidewall. It's the most common code among the 14 tires here (6 of them); tires in this size come in other load and speed ratings too.

1255Section width

255 mm across the widest point, or 10.04 inches. Every 255 size

270Aspect ratio

A percentage, not a measurement: the sidewall is 70% as tall as the tire is wide, which is 178.5 mm or 7.03 inches.

3RConstruction

Radial construction.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 6.5″ to 8.5″.

5113Load index

Each tire carries up to 2,535 lb (1,150 kg) at its maximum pressure.

6TSpeed rating

Rated for up to 118 mph sustained.

Specification	Inches	Metric
Overall diameter	32.06	814 mm
Section width	10.04	255 mm
Sidewall height	7.03	178.5 mm
Circumference	100.7	2,558 mm
Revolutions per mile (calculated, unloaded)	629.2	391 per km
Revolutions per mile (published by manufacturers)	647–648	402–403 per km
Approved wheel width	6.5–8.5	165–216 mm

Speedometer error after switching to 255/70R18

Your actual speed– mph

Questions about 255/70R18

What is 255/70R18 in inches?

32.06 inches tall, 10.04 inches wide, on a 18-inch wheel. Written in inches, that is roughly 32.1×10.0R18.

How much does a 255/70R18 tire weigh?

Between 35.3 lb and 52.3 lb for the 14 tires listed here. The lightest is the Michelin Latitude Tour HP (XL); the heaviest is the BFGoodrich All-Terrain T/A KO3 (LT D).

What wheel width do I need for 255/70R18?

Manufacturers approve 6.5–8.5″ wide wheels for this size.

How many revolutions per mile does a 255/70R18 make?

Published figures run 647–648 revolutions per mile. The calculated figure is 629.2, but manufacturers measure the tire under load, where it rolls on a smaller radius.

What is the difference between P255/70R18 and LT255/70R18?

Passenger tires (12 here) are built for passenger loads, with max loads of 2505–2756 lb. Light-truck tires (2 here) come in heavier load ranges with max loads of 2835 lb, and are usually heavier with deeper tread.

How much taller is 255/70R18 than 265/65R18?

0.49 inches taller on paper (32.06″ vs 31.56″), which raises the axle about 0.25″. Your speedometer will read about 1.6% slow.