How to Read Tire Sizes for Pickup, Light Truck and Truck/Bus Tires

Tire size markings carry the information needed to order correctly: dimensions, construction, rim diameter, load capacity and speed capability. Pickups, light trucks and heavy trucks use several notation systems that look similar but mean different things, and ordering the right size with the wrong load index is a common and potentially dangerous error. This guide explains each system.

Metric sizes: 265/65R17 112S

This format is used on passenger cars, SUVs and many pickups.

Marking	Meaning
265	Section width in millimeters
65	Aspect ratio: sidewall height as a percentage of section width
R	Radial construction
17	Rim diameter in inches
112	Load index: maximum load per tire at the specified pressure
S	Speed symbol: maximum speed at the rated load

The aspect ratio is a percentage, not a dimension. A 265/65 tire has a sidewall height of about 172 mm (65% of 265 mm).

Some tires carry a "P" prefix (P-metric, a North American passenger standard) and others carry "LT" (see below). A tire with no prefix follows the European/ISO metric system. The load ratings of P-metric and LT tires of the same size are not the same.

Load index

The load index is a code, not a weight. Selected values:

Load index	Max load per tire (kg)
104	900
106	950
112	1,120
116	1,250
120	1,400
123	1,550
143	2,725
146	3,000
150	3,350
156	4,000

The load index of replacement tires should be equal to or higher than the vehicle manufacturer's specification.

Speed symbols

Symbol	Max speed (km/h)
J	100
K	110
L	120
M	130
N	140
Q	160
R	170
S	180
T	190
H	210
V	240

Commercial truck tires are commonly rated J, K, L or M, reflecting their operating speeds and load demands. Pickup and SUV tires are commonly in the Q to H range.

LT sizes: LT265/75R16 123/120S

LT (light truck) tires are built for heavier loads and higher inflation pressures than passenger-type tires of the same dimensions. They are common on pickups used for commercial work and on 4x4 vehicles used off road.

• Dual load index (123/120). The first number applies when the tire is used singly; the second applies when used in a dual-wheel fitment.
• Load range. LT tires carry a load range letter, commonly C, D or E, equivalent to ply ratings of 6, 8 and 10. A higher load range allows higher maximum pressure and load.

Fitting a passenger-type (or P-metric) tire to a pickup specified for LT tires reduces load capacity, particularly when the bed is loaded.

Flotation sizes: 31x10.50R15LT

Flotation sizes are common on 4x4 and off-road tires:

Marking	Meaning
31	Overall diameter in inches
10.50	Section width in inches
R	Radial
15	Rim diameter in inches
LT	Light truck construction

When an importer's customers switch between flotation and metric sizes, compare overall diameter and width. A change in diameter affects speedometer accuracy, gearing, clearance and, on some vehicles, electronic stability systems. See 4x4 and all-terrain tires.

Commercial C-type sizes: 195R14C 106/104R

The "C" suffix (commercial) is a European-origin marking used on van and light commercial tires, including some pickups. Examples include 195R14C and 215/70R15C. A missing aspect ratio (as in 195R14C) indicates the older standard aspect ratio for that size. C-type tires carry a dual load index in the same way as LT tires. See pickup tires.

Tube-type light truck sizes: 7.50R16 LT

Many light trucks in export markets run tube-type tires on 16-inch rims:

• 7.50 is the nominal section width in inches.
• R indicates radial construction; a hyphen instead (7.50-16) indicates bias (cross-ply) construction.
• 16 is the rim diameter.

These tires need an inner tube and flap and are usually specified with a ply rating, for example 14PR. When ordering, confirm whether tubes and flaps are required. See light truck tires.

Truck and bus radial sizes: 11R22.5 16PR 146/143L

Two main systems are used on medium and heavy trucks and buses.

Inch-based sizes

Examples: 11R22.5, 12R22.5, 12.00R20

• 11 or 12 is the nominal section width in inches.
• 22.5 indicates a tubeless tire on a 15° drop-center rim. Half-inch rim sizes (17.5, 19.5, 22.5, 24.5) are tubeless truck sizes.
• 20 (as in 12.00R20) indicates a tube-type tire on a flat-base or multi-piece rim, used with tube and flap.

Metric low-profile sizes

Examples: 315/80R22.5, 295/80R22.5, 385/65R22.5

• Section width in millimeters, aspect ratio, radial, and rim diameter, as in passenger metric sizes.
• The 385/65R22.5 size is widely used as a trailer or steer fitment on heavy vehicles, depending on axle loads.

Load index, speed and ply rating

In 11R22.5 16PR 146/143L:

• 16PR is the ply rating, an index of strength. It does not mean the tire has 16 physical plies.
• 146/143 is the single and dual load index: 3,000 kg single, 2,725 kg per tire in dual fitment.
• L is the speed symbol (120 km/h).

Axle load and fitment position must be checked against the load index.

Position and application

Truck and bus tires are designed for a wheel position and operating condition.

Designation	Typical use
Steer	Front axle; rib tread patterns for directional stability and even wear
Drive	Driven axles; lug or block patterns for traction
Trailer	Trailer axles; designed to resist scrub and irregular wear
All-position	Mixed use, typically regional or on/off-road service
On/off-road	Construction and mining haul, with cut and chip resistance

Specify the position and application for every truck tire line. See truck and bus tires.

Date code and other sidewall markings

• DOT date code. The last four digits indicate the week and year of manufacture. 2324 means week 23 of 2024. Some markets restrict imports by tire age.
• TL / TT. Tubeless or tube type.
• M+S. Mud and snow rating, common on all-terrain tires.
• Regroovable. Some truck tires may be regrooved according to the manufacturer's guidance.
• Market approval marks. Such as E-marks or national standards marks required by some importing countries.

Ordering tires

For each line, specify size, load index and speed symbol (or ply rating), pattern or application, tubeless or tube type, and whether tubes and flaps are required. Read the size from the tire currently fitted or the vehicle placard, not from memory. Vehicle pages such as Hilux Revo and the truck parts hub help group tire requirements by fleet. Tires are volume-heavy, so see how to order mixed auto parts containers from Thailand for container planning, then upload your list.