Tire labeling (exam-
ple)
Meaning
R Tire belt design letter code for radial.
18 Rim diameter (in inches)
109 H Load rating code and speed rating code ⇒ Tire
labeling.
XL Indicates “reinforced” tire (heavy-duty)
M+S or M/S Indicates Mud and Snow capability (also M/S)
RADIAL TUBELESS Tubeless radial tire.
E4 … Labeling according to international regulations
(E) including number of the approving country.
The multi-digit approval number is listed next.
DOT BT RA TY5 1709 Tire identification number (TIN3 - In some cases
the manufacturing date is only on one side of the
tire:
DOT The tire complies with the requirements of
the United States Department of Trans-
portation, responsible for issuing safety
standards.
BT Identification letter of the manufacturing
site.
RA Manufacturer information regarding tire
dimensions.
TY5 Tire characteristics provided by the
manufacturer.
1709 Manufacturing date: 17th week in 2009.
3 TIN represents the serial number of the tire.
Accessory weight
The combined weight (in excess of those standard items which may be replaced) of automatic trans-mission, electro-mechanical power steering, power brakes, power windows, power seats, radio, and heater, to the extent that these items are available as factory-installed equipment (whether installed or not).
Aspect ratio
The ratio of sidewall height to tire width, expressed as a percentage. A number of 70 (0.7:1 or 70%) or lower indicates a low-profile tire with a shorter sidewall for improved steering response and better overall handling on dry pavement.
Bead
The part of a tire made of steel wires, wrapped or reinforced by ply cords, with the shape and structure to ensure proper fit to the wheel rim.
Bead separation
A breakdown of the bond between components in the bead.
Carcass
The tire structure, except tread and sidewall rubber which, when inflated, bears the load.
Chunking
The breaking away of pieces of the tread or sidewall.
Cord
The strands of material forming the plies in the tire.
Cord separation
The parting of cords from adjacent rubber compounds.
Cracking
Any parting within the tread, sidewall, or inner liner of the tire extending to cord material.
Cold tire inflation pressure
The tire pressure recommended by the vehicle manufacturer for a tire of a specified size that has not been driven for more than a couple of miles (kilometers) at low speeds in the 3 hour period before the tire pressure is measured or adjusted.
Curb weight
The weight of a motor vehicle with standard equipment including the maximum capacity of fuel, oil, and coolant, air conditioner, and additional weight of optional equipment.
Extra load tire
A tire designed to operate at higher loads and at higher inflation pressures than the corresponding standard tire.
Gross Axle Weight Rating (GAWR)
The load-carrying capacity of a single axle system, measured where the tire contacts the ground.
Gross Vehicle Weight Rating (GVWR)
The maximum loaded weight of the vehicle.
Groove
The space between 2 adjacent tread ribs.
Radial ply tires
A pneumatic tire in which the ply cords that extend to the beads are laid at substantially 90 degrees to the centerline of the tread.
Recommended inflation pressure
The tire pressure recommended by the vehicle manufacturer for a tire of a specified size that has not been driven for more than a couple of miles (kilometers) at low speeds in the 3 hour period before the tire pressure is measured or adjusted.
Reinforced tire
A tire designed to operate at higher loads and at higher inflation pressures than the corresponding standard tire.
Rim
The outer edge of a wheel upon which the tire beads are seated.
Rim diameter
The nominal diameter of the wheel's tire bead seating surface. If you change your wheel size, to wheels of a different diameter, you will have to purchase new tires to match the new wheels.
Rim size
Designation means rim diameter and width.
Rim type designation
The industry or manufacturer's designation for a rim by style or code.
Rim width
The nominal distance between wheel rim flanges.
Section width
The linear distance between the exteriors of the sidewalls of an inflated tire, excluding elevations due to labeling decoration, or protective bands.
Sidewall
The portion of a tire between the bead and the tread.
Sidewall separation
The parting of the rubber compound from the cord material in the sidewall.
Speed rating (letter code)
A standardized letter code indicating the maximum speed at which a tire is designed to be driven for extended periods of time. The ratings range from 93 mph or 150 km/h (“P”) to 186 mph or (300 km/h) “Y”.
The speed rating letter code, where applicable, is molded on the tire sidewall ⇒ Tire labeling. You may not find this information on all tires because it is not required by law.
Tire Pressure Monitoring System (TPMS)
A system that detects when at least one of a vehicle's tires is underinflated and illuminates a low tire-pressure warning light.
Tread
The portion of a tire that normally touches the road.