Interpretation ID: nht72-2.49

DATE: 10/18/72

FROM: C.A. BAKER FOR E.T. DRIVER -- NHTSA

TO: Bandag, Incorporated

TITLE: FMVSS INTERPRETATION

TEXT: In your letter of September 27 you suggest that Standard 117-paragraph 5.2.1(b) which relates to exposing fabric during the buffing operation of the retread process might be interpreted as forbidding the retreading of casings containing nail holes. You further quote the conclusion of an outside contractor of a Department of Transportation sponsored tire repair study that "while test wheel tests could not be passed on repaired tires, road tests showed them all to be satisfactory."

We do not consider nail holes to constitute an exposure of cord fabric within the meaning of the standard. Briefly, our examination of retread tires to date shows that nail holes which have been repaired with the repair materials vulcanized to the inside of the tire are very satisfactory. We have cut through such repairs and find them to be sound even after being subjected to Federal Motor Vehicle Safety Standards No. 109 and No. 117, Endurance and High Speed Wheel Tests. Providing the nail holes are permanently sealed on the inside of the tire they appear to be no more objectionable than the casing penetrations made by new tire manufacturers and retreaders in their awl venting procedures.

The Discussion Paper presented at the National Highway Traffic Safety Administration Technical Heating hold on April 10, 1969, contained rather detailed requirements for casings that were to be retreaded. Included within this extensive list were requirements for not retreading a casing if "two closed punctures (nail hole type) which extend through the fabric, or are less than 15" apart or are outside of the tread area." As a result of the comments received at the April 10, 1969, technical conference, at which you and Mr. Vischer attended, the Administration changed the casing condition requirements to only prohibit retreading of casing which had cord or bead wire exposed. The Administration considers the casing as part of the raw material used in the retreading process and as such, each retreader must use his exportise in casing selection prior to applying his DOT self-certification symbol.

Supplementing the above, we have noted that repairs with the repair materials not bonded to the carcass loosen during flexing and have a high incidence of failure on the Endurance and High Speed Wheel Tests.