Interpretation ID: aiam3233
P.O. Box 1311
Puyallup
Washington 98371;
Dear Mr. Pilch: This responds to your February 7, 1980 letter to the Department o Transportation, in which you complained about the failure of a tire on your truck. Specifically, you stated that the tires on the front axle of your truck were overloaded by 570 pounds each, and that no non-radial tire is currently manufactured which would not have been overloaded if used on this front axle.; If the tires which were overloaded came as original equipment on th truck, the manufacturer of the truck violated Federal Motor Vehicle Safety Standard No. 120 (49 CFR 571.120). Paragraph S5.1.2 of Standard No. 120 requires the sum of the maximum load ratings of the tires fitted to any axle to be at least equal to the gross axle weight rating of that particular axle. This requirement is applicable to all trucks manufactured on or after September 1, 1976. If your truck was manufactured after that date, please send ne the name of the manufacturer as well as the information provided by the manufacturer specifying the appropriate tire sizes to be used on the truck. The information concerning appropriate tire sizes will appear on a label on the door latch post on the driver's side of the truck. If the manufacturer has violated Standard No. 120, appropriate steps will be taken by the agency.; You also stated that certain radial tires would have met th load-carrying requirements for your truck, but that you would not use radial tires because of erratic wear patterns. For your Information, I have enclosed a booklet published by the Rubber Manufacturers Association setting forth information on the care and service of radial and non-radial truck tires. On page 11 of this booklet there is a description of the irregular wear to which you refer, as well as instructions on how to prevent irregular wear from lessening the overall mileage the tire will give you. Hence, if you wish to use radial tires on your truck, there is no reason to expect them to perform unsatisfactory.; More significant, however, is the misunderstanding you have i suggesting that no bias ply tire is manufactured which would not have been overloaded on your truck. Such a tire is now manufactured and has been manufactured for at least the past 20 years. On page 30 of the enclosed booklet, you will find a table showing the load-carrying capacity of bias ply tire sizes mounted on 15 degrees drop center rims. The tire size mounted on your truck, the 11-22.5, does indeed have a maximum load of 5,430 pounds if it is a load range F tire. However, a load range G tire of the same size has a maximum load of 6,040 pounds, and would not overload if used on your truck. This is the tire you should probably use on the front axle.; I am sorry to hear of your accident and hope that you have recovere from your injuries. Your complaint about the failure of the Uniroyal Delta tire has been recorded, and the agency will be alert to other indications of problems with this tire. To date, however, we do not have sufficient data indicating a safety problem to open a formal investigation.; I want to thank you for taking the time to express your concern abou motor vehicle safety. It is only through the efforts of concerned citizens such as yourself that we can ensure maximum safety for all users of the highway. If you have any further questions or concerns about this matter or any other aspect of highway safety, please do not hesitate to contact me.; Sincerely, Frank Berndt, Chief Counsel