tireheight.com

305/70R18 in inches

A 305/70R18 tire is 34.8″ tall and 12.0″ wide, and fits a 18″ wheel. In inches it is written 34.8×12.0R18.

Diameter34.81″
Width12.01″
Sidewall8.41″
305/70R18 drawn to scale: 34.81 inch diameter, 8.41 inch sidewall, 18 inch wheel, 12.01 inch tread width18″ wheel8.41″34.81″ overall12.01″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 305/70R18 tires really are

Heights published by BFGoodrich, Mickey Thompson and Toyo for all 6 tires in this size. Their published revolutions per mile work out to 33.8″ under load (below).

Real 305/70R18 tires measure 34.80–35.30″, against 34.81″ from the size code. They run both taller and shorter than the size code.

  1. Mickey Thompson Baja Boss A/T35.30″ +0.49″
  2. Mickey Thompson Baja Legend EXP35.10″ +0.29″
  3. Mickey Thompson Baja Legend MTZ35.10″ +0.29″
  4. BFGoodrich All-Terrain T/A KO334.80″ −0.01″
  5. BFGoodrich HD-Terrain T/A KT34.80″ −0.01″
  6. Toyo Open Country A/T III EV34.80″ −0.01″
Each bar runs from the size code's 34.81″ (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 load33.8″

Published revs per mile (596–597) mean the tire rolls like a 33.8″ tire on the vehicle. Use this for speedometer calibration.

Weight spread60.2–75.0 lb

The lightest (Toyo Open Country A/T III EV, LT E) is 14.8 lb lighter per corner than the heaviest (Mickey Thompson Baja Boss A/T, LT E).

6 tires in 305/70R18

Sort by the spec you care about.

LoadRevs/miSource
Toyo Open Country A/T III EVAll-terrainLT E · 126/123R34.8060.216.83,750596Spec page
Mickey Thompson Baja Legend EXPAll-terrainLT E · 126Q35.1065.018.53,750–Spec page
BFGoodrich All-Terrain T/A KO3All-terrainLT F · 128S34.8069.416.03,970597Spec page
Mickey Thompson Baja Legend MTZMud-terrainLT E · 126Q35.1070.021.03,750–Spec page
BFGoodrich HD-Terrain T/A KTLT F · 128Q34.8074.518.03,970597Spec page
Mickey Thompson Baja Boss A/TAll-terrainLT E · 126Q35.3075.018.53,750–Spec page

Is 305/70R18 a 35-inch tire?

≈35″

Yes. The size code works out to 34.81″, and the 6 tires here publish 34.80–35.30″, so people call it a 35.

All 35-inch tire sizes, on every wheel size.

A true 35×12.50R18 is 0.19″ taller on paper and 0.5″ wider.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 305/70R18Difference
285/70R1833.71-1.10″-3.2%
295/70R1834.26-0.55″-1.6%
295/75R1734.42-0.39″-1.1%
325/65R1834.63-0.18″-0.5%
285/75R1834.83+0.02″+0.1%
35×12.50R1835.00+0.19″+0.5%
35×10.50R1735.00+0.19″+0.5%
35×11.50R1735.00+0.19″+0.5%
35×12.50R1735.00+0.19″+0.5%
315/70R1835.36+0.55″+1.6%

How to read 305/70R18

How to read any tire size

LT305/70R18 126Q as printed on the tire sidewall, with each part numberedLT305/70R18 126Q1234567
How LT305/70R18 126Q is printed on the sidewall. It's the most common code among the 6 tires here (3 of them); tires in this size come in other load and speed ratings too.
1LTLight truck

Marks a light truck (LT) tire.

2305Section width

305 mm across the widest point, or 12.01 inches. Every 305 size

370Aspect ratio

A percentage, not a measurement: the sidewall is 70% as tall as the tire is wide, which is 213.5 mm or 8.41 inches.

4RConstruction

Radial construction.

518Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 8.0″ to 10.0″.

6126Load index

Each tire carries up to 3,750 lb (1,700 kg) at its maximum pressure.

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 3,750 lb each, as published.

SpecificationInchesMetric
Overall diameter34.81884 mm
Section width12.01305 mm
Sidewall height8.41213.5 mm
Circumference109.42,778 mm
Revolutions per mile (calculated, unloaded)579.4360 per km
Revolutions per mile (published by manufacturers)596–597370–371 per km
Approved wheel width8.0–10.0203–254 mm

Speedometer error after switching to 305/70R18

Your actual speed– mph

Questions about 305/70R18

What is 305/70R18 in inches?

34.81 inches tall, 12.01 inches wide, on a 18-inch wheel. Written in inches, that is roughly 34.8×12.0R18.

How much does a 305/70R18 tire weigh?

Between 60.2 lb and 75.0 lb for the 6 tires listed here. The lightest is the Toyo Open Country A/T III EV (LT E); the heaviest is the Mickey Thompson Baja Boss A/T (LT E).

What wheel width do I need for 305/70R18?

Manufacturers approve 8.0–10.0″ wide wheels for this size.

How many revolutions per mile does a 305/70R18 make?

Published figures run 596–597 revolutions per mile. The calculated figure is 579.4, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 305/70R18 than 325/65R18?

0.18 inches taller on paper (34.81″ vs 34.63″), which raises the axle about 0.09″. Your speedometer will read about 0.5% slow.