Stronger tests, stronger tires

Higher standards will result when final rule is issued

On Nov. 13, 1973, the Dept. of Transportation (DOT) established the current testing standard for tires on vehicles with a gross vehicle weight rating of 10,000 lbs. or more. It was intended to ensure that tires were constructed in a manner that could withstand the operational conditions associated with trucks. It also required markings on the sidewall so the user would know the load-carrying capacity as well as other important information. After the manufacturer determined that a tire could pass those performance tests and comply with the sidewall labeling requirements, they would mold the letters “DOT” on the lower sidewall to indicate compliance with Federal Motor Vehicle Safety Standard (FMVSS) 49 CFR 571.119.

Fast forward 27 years and updates to the regulation had not been considered until a passenger tire recall prompted Congress to direct the National Highway Traffic and Safety Administration (NHTSA) to update the testing requirements for all tires. It’s an understatement to suggest that tire manufacturing technology had changed since then, while operational changes to trucking have undergone significant changes as well. In other words, the tires that were tested on the trucks that operated in 1973 are nothing like the tires or trucks that operated in 2000.

Fast forward another 10 years and NHTSA released a notice of proposed rulemaking (NPRM) for an update to FMVSS 571.119 that would include more stringent endurance tests as well as a high-speed test. For tire manufacturers, this definitely raises the bar for durability and performance. Under the proposal, they would be required to build tires that are more resistant to underinflation at higher speeds. For example, the current testing requirements call for the inflation pressure to be set at the level for the maximum load molded on the sidewall, while the new proposal calls for the inflation pressure to be set at 80% of the value listed for the maximum load. That’s a huge difference.

The NPRM also proposed the addition of a maximum speed rating on the sidewall as an actual numerical value instead of the alphabetical speed symbols used internationally to make it clearer to fleets of all sizes.

Recent remarks from a senior NHTSA official indicated that the new testing standards for truck tires should be released during this year. Some form of new endurance and high-speed tests are all but certain, but there has been no communication on whether or not the maximum speed rating on the sidewall will be reflected as a numerical value or the international speed symbol used by the rest of the world. It’s also important to note that while retreaded tires were tested along with new tires between the Congressional mandate in 2000 and the NPRM in 2010 to help guide and develop the new standard, it does not appear that 571.119 will include retreads.

Until the final rule is published, we can only speculate on what type of impact it will have on the tire and transportation industries. The higher performance standards will probably mean that some of the offshore brands may have difficulty passing the tests. Even without knowing the details, it’s still safe to say that the next generation of truck tires with the DOT certification on the sidewall will have to be a lot more durable than they were in 1973, and that should be good news for trucking.

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