Interpretation ID: nht87-3.12

TYPE: INTERPRETATION-NHTSA

DATE: OCTOBER 8, 1987

FROM: WES SPRUNK -- SAF-TEE SIPING & GROOVING INC.

TO: ERIKA JONES -- NHTSA CHIEF COUNSEL

TITLE: NONE

ATTACHMT: DECEMBER 30, 1988 LETTER FROM JONES TO SPRUNK, BROCHURES ON TIRE SIPING, 1978 NSC WINTER TEST REPORT, AUGUST 19, 1986 LETTER FROM KEIL TO SPRUNK, ARTICLE FROM AUGUST 1986 ISSUE OF "SCHOOL BUSINESS AFFAIRS," ARTICLE ENTITLED "SLASHING TIRES FOR SAFETY AND SAVINGS" FROM DECEMBER 1984 "NATIONAL SCHOOL BUS REPORT," MARCH 20, 1985 LETTER FROM GIFFORD TO SPRUNK, OCTOBER 15, 1982 LETTER FROM PALMER TO MARCY MANUFACTURING, AND APRIL 1983 AND APRIL 1984 ARTICLES FROM "GW SAFETY TALK"

TEXT: I have had a phone conversation with Ed Clancy concerning some problems that have arisen in reference to my product - with clarification from the National Highway Traffic Association.

I spoke, first of all, with Neil Thomas of the Federal Highway Administration and, later, with Jim Birtell, Head Engineer; they informed me that there was no problem with their department concerning siping tires in reference to the Federal Highway Admini stration. But, there was some question with a possible customer of mine with D.O.T.

For that reason, I would like to explain siping because, at this point, it is referred to in the D.O.T. Regulations in the same reference as grooving. We manufacturer and distribute both siping and grooving machines and I would like to clarify our posit ion and the difference in the two operations.

Grooving is a process of removing rubber from the tire to give it an additional space for water release. We sell grooving machines mainly to the metro bus companies who lease their tires and have considerable undertread.

Siping is a process of cross cutting the tread, never deeper than the original tread depth of the tire; and in most cases, 1/32" less, with a fine knife-either four of five cuts to the inch-that does not remove rubber. We have people siping tires on tru cks, buses, and passenger with excellent results. But, we have had some government agencies that want more clarification from your department.

I have enclosed for you a brochure on our siping machine and several testimonials from customers concerning their experience with siping so that you can better understand the process and the benefits derived thereform. In the cross cutting of the tread, the benefits are that it allows the tread to interact with the road and have the edges grap the road for better traction. It also allows for the tread components to open up enough to allow air to get into the tread and this helps with the increase in w ear by cooling the tread of the tire.

What I need to know from you is if there is any possible problem with the siping of new, used, truck, passenger, or light duty tires, assuming the siping is done as I stated above, with D.O.T. Regulations

Enc.