nht72-6.42 | NHTSA

DATE: 08/29/72

FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA

TO: B. F. Goodrich Tire Company

TITLE: FMVSR INTERPRETATION

TEXT: This is in response to your petition for rulemaking, submitted July 30, 1971, to amend Motor Vehicle Safety Standard No. 109 (49 CFR @ 571.109) and the Tire Identification and Recordkeeping Regulations (49 CFR Part 574). Your petition requests that Standard No. 109 be amended to provide for a special tire category for folding sidewall-reduced tread tires, of which the "Space Saver Spare" tire you manufacture is an example. You request specifically that requirements for these tires differ from conventional tires as follows: lower minimum breaking-energy values in the strength test (S4.2.2.4, Table II); modified minimum size factors for certain tire size designations which you list; elimination of the condition that the tire be mounted without lubricant for the bead unseating test (S4.2.2.3); and allowing the tire identification number to be placed on the lower sidewall (49 CFR 574.5). For the reasons stated below, your petition is hereby denied insofar as it requests modifications to the strength and bead unseating requirements of Standard No. 109, and the requirements of Part 574. We make certain recommendations herein regarding your request for modification of the minimum size factors of Standard No. 109.

The basis for your request for lower breaking-energy values in the strength test is that the values you request represent a level of performance equal to that of a conventional tire having the same amount of tread remaining as a new folding sidewall-reduced tread tire. The NHTSA cannot accept this argument as a valid basis for specifying lower breaking-energy value requirements for folding sidewall-reduced tread tires The requirements specified for the strength test are considered to be necessary minimum requirements for all new passenger car tires. Consequently, persons who purchase new tires, regardless of their construction, are entitled to at least this level of performance, and not the level of performance represented by a used tire.

The NHTSA does not believe, similarly, that you have presented a sufficient basis for elimination of the condition, in the bead unseating test procedure, that the tire be mounted for the test without the use of lubricant. While the NHTSA concurs in the benefits of run-flat performance, which the "Space Saver Spare" appears to provide, we do not believe that this advantage outweighs the necessity that the tire conform to the bead unseating requirements when mounted without lubrication. The NHTSA believes the possibility that tires will be mounted without lubrication in the field is sufficiently great to warrant the retention of this condition in the standard's test procedure.

We also do not consider sufficient the justification you provide for your request that the identification number required pursuant to Part 574 be allowed to be placed on the lower sidewall of the tire. Your statement to the effect that no problems are presented if the number "wears off" ignores the fact that the number must be retained on the tire for purposes of identification should a defect notification or recall campaign be instituted.

With reference to your request for modification of the (Illegible Word) size factor for the tire size designations which you list, believe B. F. Goodrich should petition, in accordance with guidelines published October 5, 1968 (33 F.R. 14964), to amend the Appendices of Standards Nos. 109 and 110 to provide that folding sidewall-reduced tread tires be added as a separate tire type, including new size designations and corresponding values for section width and minimum size factor that you consider appropriate.

[GRAPHICS OMITTED]

Interpretation ID: nht72-6.42