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285/70R18 in inches

A 285/70R18 tire is 33.7″ tall and 11.2″ wide, and fits a 18″ wheel. In inches it is written 33.7×11.2R18.

Diameter33.71″
Width11.22″
Sidewall7.85″
285/70R18 drawn to scale: 33.71 inch diameter, 7.85 inch sidewall, 18 inch wheel, 11.22 inch tread width18″ wheel7.85″33.71″ overall11.22″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 285/70R18 tires really are

Heights published by BFGoodrich and Toyo for all 5 tires in this size. Their published revolutions per mile work out to 32.7–33.1″ under load (below).

Real 285/70R18 tires measure 33.70–34.09″, against 33.71″ from the size code. They run both taller and shorter than the size code.

  1. Toyo Open Country M/T34.09″ +0.39″
  2. Toyo Open Country A/T III33.74″ +0.03″
  3. BFGoodrich All-Terrain T/A KO333.70″ −0.01″
  4. BFGoodrich Mud-Terrain T/A KM333.70″ −0.01″
  5. Toyo Open Country R/T Pro33.70″ −0.01″
Each bar runs from the size code's 33.71″ (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 load32.7–33.1″

Published revs per mile (609–616) mean the tire rolls like a 32.7–33.1″ tire on the vehicle. Use this for speedometer calibration.

Weight spread57.4–70.3 lb

The lightest (Toyo Open Country A/T III, LT E) is 13.0 lb lighter per corner than the heaviest (Toyo Open Country M/T, LT E).

5 tires in 285/70R18

Sort by the spec you care about.

LoadRevs/miSource
Toyo Open Country A/T IIIAll-terrainLT E · 127/124S33.7457.416.53,860616Spec page
BFGoodrich All-Terrain T/A KO3All-terrainLT E · 127S33.7062.216.03,860616Spec page
Toyo Open Country R/T ProRugged-terrainLT E · 127/124Q33.7067.117.13,860616Spec page
BFGoodrich Mud-Terrain T/A KM3Mud-terrainLT E · 127Q33.7069.218.03,860616Spec page
Toyo Open Country M/TMud-terrainLT E · 127/124Q34.0970.318.93,860609Spec page

Is 285/70R18 a 34-inch tire?

≈34″

Yes. The size code works out to 33.71″, and the 5 tires here publish 33.70–34.09″, so people call it a 34.

All 34-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 285/70R18Difference
235/80R1832.80-0.91″-2.7%
33×12.50R1833.00-0.71″-2.1%
275/70R1833.16-0.55″-1.6%
325/60R1833.35-0.35″-1.1%
305/65R1833.61-0.10″-0.3%
305/70R1733.81+0.10″+0.3%
285/75R1733.83+0.12″+0.4%
34×10.50R1734.00+0.29″+0.9%
295/70R1834.26+0.55″+1.6%
325/65R1834.63+0.93″+2.7%

How to read 285/70R18

How to read any tire size

LT285/70R18 127/124Q as printed on the tire sidewall, with each part numberedLT285/70R18 127/124Q1234567
How LT285/70R18 127/124Q is printed on the sidewall. It's the most common code among the 5 tires here (2 of them); tires in this size come in other load and speed ratings too.
1LTLight truck

Marks a light truck (LT) tire.

2285Section width

285 mm across the widest point, or 11.22 inches. Every 285 size

370Aspect ratio

A percentage, not a measurement: the sidewall is 70% as tall as the tire is wide, which is 199.5 mm or 7.85 inches.

4RConstruction

Radial construction.

518Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 7.5″ to 9.5″.

6127/124Load index

Each tire carries up to 3,860 lb (1,750 kg) on its own, or 3,525 lb (1,600 kg) each when paired on a dual rear axle.

7QSpeed rating

Rated for up to 99 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 3,860 lb each, as published.

SpecificationInchesMetric
Overall diameter33.71856 mm
Section width11.22285 mm
Sidewall height7.85199.5 mm
Circumference105.92,690 mm
Revolutions per mile (calculated, unloaded)598.3372 per km
Revolutions per mile (published by manufacturers)609–616378–383 per km
Approved wheel width7.5–9.5191–241 mm

Speedometer error after switching to 285/70R18

Your actual speed– mph

Questions about 285/70R18

What is 285/70R18 in inches?

33.71 inches tall, 11.22 inches wide, on a 18-inch wheel. Written in inches, that is roughly 33.7×11.2R18.

How much does a 285/70R18 tire weigh?

Between 57.4 lb and 70.3 lb for the 5 tires listed here. The lightest is the Toyo Open Country A/T III (LT E); the heaviest is the Toyo Open Country M/T (LT E).

What wheel width do I need for 285/70R18?

Manufacturers approve 7.5–9.5″ wide wheels for this size.

How many revolutions per mile does a 285/70R18 make?

Published figures run 609–616 revolutions per mile. The calculated figure is 598.3, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 285/70R18 than 305/65R18?

0.10 inches taller on paper (33.71″ vs 33.61″), which raises the axle about 0.05″. Your speedometer will read about 0.3% slow.