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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Proposed Rules
RIN to each regulatory action listed in the Unified Agenda of Federal Regulations. The Regulatory Information Service Center publishes the Unified Agenda in April and October of each year. You may use the RIN contained in the heading at the beginning of this document to find this action in the Unified Agenda.

571.121; 571.122; 571.126; 571.135;
571.136; 571.139; 571.500.

3. Amend 571.105 by removing paragraphs S6.9.2a and S6.9.2b and adding paragraph S6.9.2 to read as follows:

List of Subjects

49 CFR Part 571
Imports, Incorporation by reference, Motor vehicle safety, Reporting and recordkeeping requirements, Tires.
49 CFR Part 575
Consumer protection, Incorporation by reference, Motor vehicle safety, Reporting and recordkeeping requirements, Tires.
In consideration of the foregoing, NHTSA proposes to amend 49 CFR
parts 571 and 575 as follows:
PART 571FEDERAL MOTOR
VEHICLE SAFETY STANDARDS
1. The authority citation for part 571
of title 49 continues to read as follows:

Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95.

2. Amend 571.5 by revising paragraphs d33 through 35 to read as follows:

571.5

Matter incorporated by reference.

d
33 ASTM E133719, Standard Test Method for Determining Longitudinal Peak Braking Coefficient PBC of Paved Surfaces Using Standard Reference Test Tire, approved December 1, 2019, into 571.105; 571.121; 571.122; 571.126;
571.135; 571.136; 571.500.
34 ASTM F180520, Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snowand Ice-Covered Surfaces, approved May 1, 2020, into 571.139.
35 ASTM F249319, Standard Specification for P225/60R16 97S Radial Standard Reference Test Tire, approved Oct. 1, 2019, into 571.105;

571.105 Standard No. 105; Hydraulic and electric brake systems.

S6.9.2 a For vehicles with a GVWR
greater than 10,000 pounds, road tests excluding stability and control during braking tests are conducted on a 12foot-wide, level roadway, having a peak friction coefficient of 1.02 when measured using an ASTM F249319
incorporated by reference, see 571.5, standard reference test tire, in accordance with ASTM E133719
incorporated by reference, see 571.5, at a speed of 40 mph, without water delivery. Burnish stops are conducted on any surface. The parking brake test surface is clean, dry, smooth, Portland cement concrete.
b For vehicles with a GVWR greater than 10,000 pounds, stability and control during braking tests are conducted on a 500-foot-radius curved roadway with a wet level surface having a peak friction coefficient of 0.55 when measured on a straight or curved section of the curved roadway using an ASTM
F249319 standard reference tire, in accordance with ASTM E133719 at a speed of 40 mph, with water delivery.

4. Amend 571.121 by revising paragraphs S5.3.1.1 introductory text, S5.3.6.1, S5.7.1, S6.1.7, Table I, Table II, and Table IIa to read as follows:
571.121
systems.

Standard No. 121; Air brake

S5.3.1.1 Stop the vehicle from 60
mph on a surface with a peak friction coefficient of 1.02 with the vehicle loaded as follows:

S5.3.6.1 Using a full-treadle brake application for the duration of the stop, stop the vehicle from 30 mph or 75
percent of the maximum drive-through speed, whichever is less, on a 500-foot
radius curved roadway with a wet level surface having a peak friction coefficient of 0.55 when measured on a straight or curved section of the curved roadway using an ASTM F249319 incorporated by reference, see 571.5 standard reference tire, in accordance with ASTM
E133719 incorporated by reference, see 571.5, at a speed of 40 mph, with water delivery.

S5.7.1 Emergency brake system performance. When stopped six times for each combination of weight and speed specified in S5.3.1.1, except for a loaded truck tractor with an unbraked control trailer, on a road surface having a PFC of 1.02, with a single failure in the service brake system of a part designed to contain compressed air or brake fluid except failure of a common valve, manifold, brake fluid housing, or brake chamber housing, the vehicle shall stop at least once in not more than the distance specified in Column 5 of Table II, measured from the point at which movement of the service brake control begins, except that a trucktractor tested at its unloaded vehicle weight plus up to 1,500 pounds shall stop at least once in not more than the distance specified in Column 6 of Table II. The stop shall be made without any part of the vehicle leaving the roadway, and with unlimited wheel lockup permitted at any speed.

S6.1.7 Unless otherwise specified, stopping tests are conducted on a 12foot wide level, straight roadway having a peak friction coefficient of 1.02. For road tests in S5.3, the vehicle is aligned in the center of the roadway at the beginning of a stop. Peak friction coefficient is measured using an ASTM
F249319 standard reference test tire see ASTM F249319 incorporated by reference, see 571.5 in accordance with ASTM E133719 incorporated by reference, see 571.5, at a speed of 40
mph, without water delivery for the surface with PFC of 1.02, and with water delivery for the surface with PFC
of 0.55.

khammond on DSKJM1Z7X2PROD with PROPOSALS

TABLE ISTOPPING SEQUENCE
Truck tractors Burnish S6.1.8
Stability and Control at GVWR S5.3.6
Stability and Control at LLVW S5.3.6
Manual Adjustment of Brakes
60 mph Service Brake Stops at GVWR S5.3.1
60 mph Emergency Service Brake Stops at GVWR S5.7.1

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