Distr.

GENERAL

TRANS/WP.29/GRB/1999/9

6 July 1999

Original: ENGLISH

ECONOMIC COMMISSION FOR EUROPE

INLAND TRANSPORT COMMITTEE

Working Party on the Construction of Vehicles

Working Party on Noise (GRB)

(Thirty-first session, 16 and 17 September 1999,

agenda item 1.)

PROPOSAL FOR ADDITIONAL AMENDMENTS TO THE DRAFT REGULATION CONCERNING THE APPROVAL OF TYRES WITH REGARD TO ROLLING SOUND EMISSIONS

(Document TRANS/WP.29/GRB/1999/3)

Transmitted by the Expert from Japan

Note: The text reproduced below was prepared by the expert from Japan. It contains some amendments concerning the fitting of tyres of classes C2 and C3 on the test vehicle and the interpretation of test results.

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Note:	This document is distributed to the Experts on Noise only.

GE.99-

Paragraph 2.5.1., amend to read:

"...... The tyres shall have full tread depth prior to run-in.

However, in the case of Classes C2 and C3 tyres with no special fitting requirements, only two of these tyres shall be fitted on the rear rims while low-noise dummy tyres (having a tread depth of not less than 1.6 mm and available on the market) which suit the axle load shall be fitted on the front rims, and then the tests prescribed in paragraph 2.5.2. and thereafter shall be performed.

Tyres are to be tested on rims permitted by the tyre manufacturer."

Paragraph 3.1., add at the end:

"The noise level of dummy tyres alone may be measured separately, and subtracted from the noise measurement result obtained from paragraph 4.3. Therefore, a total of four dummy tyres may be fitted on the front and rear rims of a test vehicle, and the tests prescribed in paragraphs 2.5.2. to 4.3. performed. The result thus obtained, after subtraction of [3] dB(A), shall be regarded as the noise level (Ld) of the front dummy tyres. This noise value Ld and the noise value Lt, which is derived in paragraph 4.3. from the aforementioned test vehicle, fitted with front dummy tyres and rear tyres with no special fitting requirements, shall be applied to the following equation to obtain the value of L:

L = 10 log10 [10(Lt/10) - 10(Ld/10)]"

Paragraph 4.3., amend to read:

"..........

ref = 20 C

For Class C1 tyres, the coefficient K is -0.05 dB(A)/°C.

For Class C2....... "