Tire Standards

The load index on a tire gives a numerical value for the maximum weight the tire can support when it is inflated to its recommended pressure. Passenger tires have only one load index on the sidewall of the tire where light truck tires have two load index ratings. The light truck tires have two load…

The Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) system which establishes ratings for treadwear, traction, and temperature resistance. It is important to note that these tests are conducted independently by each manufacturer and not by the Department of Transportation. The treadwear rating (440) refers to…

THE LETTERS “P” AND “LT” For most vehicles, you’ll see the letter “P” before the number sequence begins: P225/70R16 91S. The “P” is short for “P-metric” which is a designation by the Tire and Rim Association for a “passenger car” tire type. This signifies the tire was designed to primarily be used on passenger vehicles, which…

JATMA was established in September 26, 1947. To contribute to the development of the industry and economy of our country, and improvement of national life, JATMA OBJECTIVES Conducts research on production, distribution, consumption and trade of the automobile tyres (automobile tyres, off the road tyres, Industrial tyres, tyres for agricultural tractors and machines, etc.) Plan…

The Tire and Rim Association, Incorporated, is the technical standardizing body of the tire, rim, valve and allied part manufacturers for the United States. It was organized in 1903 when passenger car users were greatly inconvenienced because each make of tire required its own special rim. This situation, coupled with the fact that there were…

E.T.R.T.O. WAS FOUNDED IN OCTOBER 1964 BUT PREVIOUSLY, FROM 1956 TO 1964, IT WAS KNOWN AS THE EUROPEAN TYRE AND WHEEL TECHNICAL CONFERENCE (ETWTC). Its principal objects, as stated in the current E.T.R.T.O. Constitution dated October 2019, are as follows : To further align of national standards and ultimately to achieve interchangeability of pneumatic tyres,…

A “Z” rating can mean different things. While it nearly always means a high performance tire for high-performing sports cars, “Z” may actually appear in the middle of a tire’s size information. When it does, it represents either a maximum speed of more than 149 mph (240 kph) or 186 mph (300 kph). Which of…

Flotation tires is an alternate format of tire sizing. Flotation tire sizes are typically larger truck tires, but ATV/UTV tires also fall into this category. The major difference between a flotation tire and a metric tire is that flotation tires is measured in inches and metric tires in millimeters (except for diameter, which is measured…