FMVSS 106: Brake hoses explained.

What FMVSS 106 says it is for

The eCFR heads this section "Standard No. 106; Brake hoses." Under 49 CFR part 571, the Federal Motor Vehicle Safety Standards are the numbered standards that set safety performance requirements for motor vehicles and equipment. The text below is quoted from 571.106 as current through October 29, 2026.

This standard specifies labeling and performance requirements for motor vehicle brake hose, brake hose assemblies, and brake hose end fittings.

The purpose of this standard is to reduce deaths and injuries occurring as a result of brake system failure from pressure or vacuum loss due to hose or hose assembly rupture.

What it applies to

The application section of the standard says:

This standard applies to passenger cars, multipurpose passenger vehicles, trucks, buses, trailers, and motorcycles, and to hydraulic, air, and vacuum brake hose, brake hose assemblies, and brake hose end fittings for use in those vehicles.

Whether a particular vehicle or part is covered depends on the standard's text as written, including any exclusions and date-specific rules. This page does not decide that for you.

How the standard is organized

The eCFR text of 571.106 has these top-level sections:

• S1: Scope
• S2: Purpose
• S3: Application
• S4: Definitions
• S5: Requirements—hydraulic brake hose, brake hose assemblies, and brake hose end fittings
• S6: Test procedures—Hydraulic brake hose, brake hose assemblies, and brake hose end fittings
• S7: Requirements—Air brake hose, brake hose assemblies, and brake hose end fittings
• S8: Test procedures—Air brake hose, brake hose assemblies, and brake hose end fittings
• S9: Requirements—vacuum brake hose, brake hose assemblies, and brake hose end fittings
• S10: Test procedures—Vacuum brake hose, brake hose assemblies, and brake hose end fittings
• S11: Requirements—Plastic air brake tubing, plastic air brake tubing assemblies, and plastic air brake tubing end fittings
• S12: Test procedures—Plastic air brake tubing, plastic air brake tubing assemblies, plastic air brake tubing end fittings
• S13: Test Conditions

In all, the text has 187 numbered headings. Use the finder above to search them. A search for "test", for example, lists the headings that mention tests.

Key requirements, quoted from the text

These are excerpts from the requirements sections of 571.106, in the order the standard presents them. Long paragraphs are shortened where marked; the eCFR has the complete text, tables and figures, which this page omits.

How to read the numbers in these excerpts: they are test conditions, not limits on what a hose may carry in service. S6.2 holds a hydraulic hose at 4,000 psi of water pressure for 2 minutes before raising it further. S8.1 conditions an air brake hose for 70 hours at 212 degrees Fahrenheit (100 degrees Celsius), and S8.2 does the same at minus 40 degrees Fahrenheit. They show how severe the lab conditions are, which is the point of a heat, cold and pressure test. They do not show the pass criteria, which sit in the requirements paragraphs and some of which are shortened here. To find the rule that governs a given test, match the S number: S5.3 points to the S6 procedures, S7.3 to S8, S9.2 to S10 and S11.3 to S12.

S5.1 Construction. (a) Each hydraulic brake hose assembly shall have permanently attached brake hose end fittings which are attached by deformation of the fitting about the hose by crimping or swaging. (b) Each hydraulic brake hose assembly that is equipped with a permanent supplemental support integrally attached to the assembly and is manufactured as a replacement for use on a vehicle not equipped, as an integral part of the vehicle's original design, with a means of attaching the support to the vehicle shall be equipped with a bracket that is integrally attached to the supplemental support and that adapts the vehicle to properly accept this type of brake hose assembly.

S5.3 Test requirements. A hydraulic brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S6. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having been subjected to and having met the constriction requirement (S5.3.1) and any one of the requirements specified in S5.3.2 through S5.3.13.

S6.1.1 Apparatus. Utilize a test apparatus (as shown in Figure 1) which consists of: (a) Source for required fluid pressure; (b) Test fluid of water without any additives and free of gases; (c) Reservoir for test fluid; (d) Pressure gauges;

S6.2 Burst strength test. (a) Connect the brake hose to a pressure system and fill it completely with water, allowing all gases to escape. (b) Apply water pressure of 4,000 psi at a rate of 15,000 psi per minute. (c) After 2 minutes at 4,000 psi, increase the pressure at the rate of 15,000 psi per minute until the pressure exceeds 5,000 psi for a brake hose larger than 1/8 inch or 3 mm diameter, or until the pressure exceeds 7,000 psi for a brake hose of 1/8 inch, 3 mm, or smaller diameter.

S6.3.1 Apparatus. Utilize test apparatus that is dynamically balanced and includes: (a) A movable header consisting of a horizontal bar equipped with capped end fittings and mounted through bearings at each end to points 4 inches from the center of two vertically rotating disks whose edges are in the same vertical plane; (b) An adjustable stationary header parallel to the movable header in the same horizontal plane as the centers of the disks, and fitted with open end fittings; (c) An elapsed time indicator; and (d) A source of water pressure connected to the open end fittings.

S6.4 Tensile strength test. Utilize a tension testing machine conforming to the requirements of ASTM E4-03 (incorporated by reference, see § 571.5) and provided with a recording device to measure the force applied.

S6.5 Water absorption sequence tests. (a) Prepare three brake hose assemblies and measure the free length of the hose assemblies. (b) Immerse the brake hose assemblies in distilled water at 185 degrees Fahrenheit (85 degrees Celsius) for 70 hours. Remove the brake hose assemblies from the water and condition in air at room temperature for 30 minutes. (c) Conduct the tests in S6.2, S6.3, and S6.4, using a different hose for each sequence.

S7.1 Construction. Each air brake hose assembly shall be equipped with permanently attached brake hose end fittings or reusable brake hose end fittings. Each air brake hose constructed of synthetic or natural elastomeric rubber shall conform to the dimensional requirements specified in Table III, except for brake hose manufactured in metric sizes.

S7.2.1 Hose. Each air brake hose shall be labeled, or cut from bulk hose that is labeled, at intervals of not more than 6 inches, measured from the end of one legend to the beginning of the next, in block capital letters and numerals at least one-eighth of an inch high, with the information listed in paragraphs (a) through (e) of this section. The information need not be present on hose that is sold as part of a brake hose assembly or a motor vehicle. (a) The symbol DOT, constituting a certification by the hose manufacturer that the hose conforms to all applicable motor vehicle safety standards. [excerpt continues in the eCFR]

S7.3 Test requirements. Each air brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S8. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having met the constriction requirement (S7.3.1) and then having been subjected to any one of the requirements specified in S7.3.2 through S7.3.13.

S8.1 High temperature resistance test. (a) Utilize a small test cylinder with a radius specified in Table IV for the size of hose tested. (b) Bind the hose around the cylinder and condition it in an air oven for 70 hours at 212 degrees Fahrenheit (100 degrees Celsius). (c) Cool the hose to room temperature, remove it from the cylinder and straighten it. (d) Without magnification, examine the hose externally and cut the hose lengthwise and examine the inner tube.

S8.2 Low temperature resistance test. (a) Utilize a large test cylinder with a radius specified in Table IV for the size of hose tested. (b) Condition the cylinder and the brake hose, in a straight position, in a cold box at minus 40 °F. for 70 hours. (c) With the hose and cylinder at minus 40 degrees Fahrenheit (minus 40 degrees Celsius), bend the hose 180 degrees around the cylinder at a steady rate in a period of 3 to 5 seconds. Remove the hose from the test cylinder and visibly examine the exterior of the hose for cracks without magnification. (d) Allow the hose to warm at room temperature for 2 hours. All reusable end fittings are removed from the hose. [excerpt continues in the eCFR]

S8.3 Oil resistance test. Utilize three test specimens and average the results.

S8.4 Ozone resistance test. Conduct the test specified in S6.8, using air brake hose, except use the large test cylinder specified in Table IV for the size of hose tested.

S8.5 Length change test. (a) Position a test hose in a straight, horizontal position, and apply air pressure of 10 psi thereto. (b) Measure the hose to determine original free length. (c) Without releasing the 10 psi, raise the air pressure to the test hose to 200 psi. (d) Measure the hose under 200 psi to determine final free length. An elongation or contraction is an increase or decrease, respectively, in the final free length from the original free length of the hose.

S9.1.1 Hose. Each vacuum brake hose shall be labeled, or cut from bulk hose that is labeled, at intervals of not more than 6 inches, measured from the end of one legend to the beginning of the next, in block capital letters and numerals at least one-eighth of an inch high, with the information listed in paragraphs (a) through (e) of this section. The information need not be present on hose that is sold as part of a brake hose assembly or a motor vehicle. (a) The symbol DOT, constituting a certification by the hose manufacturer that the hose conforms to all applicable motor vehicle safety standards. [excerpt continues in the eCFR]

S9.2 Test requirements. Each vacuum brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S10. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having met the constriction requirement (S9.2.1) and then having been subjected to any one of the requirements specified in S9.2.2 through S9.2.10.

S10.1 High temperature resistance test. (a) Measure the initial outside diameter of the hose. (b) Subject the hose to an internal vacuum of 26 inches of Hg at an ambient temperature of 257 degrees Fahrenheit (125 degrees Celsius) for a period of 96 hours. Remove the hose to room temperature and atmospheric pressure. (c) Within 5 minutes of completion of the conditioning in S10.1(b), measure the outside diameter at the point of greatest collapse and calculate the percentage collapse based on the initial outside diameter. (d) Cool the hose at room temperature for 5 hours. Bend the hose around a mandrel with a diameter equal to five times the initial outside diameter of the hose. Examine the exterior of the hose for cracks, charring, or disintegration visible without magnification. [excerpt continues in the eCFR]

S10.2 Low temperature resistance test. (a) Conduct the test specified in S8.2(a) through (c) using vacuum brake hose with the cylinder radius specified in Table V for the size of hose tested. (b) Remove the hose from the test cylinder, warm the hose at room temperature for 5 hours, and conduct the hydrostatic pressure test in S10.1(e).

S10.3 Ozone resistance test. Conduct the test specified in S6.8 using vacuum brake hose.

S10.4 Burst strength test. Conduct the test specified in S8.8 using vacuum brake hose.

S10.5 Vacuum test. Utilize a 12-inch vacuum brake hose assembly sealed at one end. (a) Measure the hose outside diameter. (b) Attach the hose to a source of vacuum and subject it to a vacuum of 26 inches of Hg for 5 minutes. (c) Measure the hose to determine the minimum outside diameter while the hose is still subject to vacuum.

S11 Requirements—Plastic air brake tubing, plastic air brake tubing assemblies, and plastic air brake tubing end fittings. 11.1 Construction. Each plastic air brake tubing assembly shall be equipped with permanently attached end fittings or reusable end fittings. Plastic air brake tubing shall conform to the dimensional requirements specified in Table VII. (S12.1)

S11.2.1 Plastic air brake tubing. Plastic air brake tubing shall be labeled, or cut from bulk tubing that is labeled, at intervals of not more than 6 inches, measured from the end of one legend to the beginning of the next, in block capital letters and numerals at least one-eighth of an inch high, with the information listed in paragraphs (a) through (e) of this section. The information need not be present on tubing that is sold as part of a motor vehicle. (a) The symbol DOT, constituting a certification by the hose manufacturer that the hose conforms to all applicable motor vehicle safety standards. [excerpt continues in the eCFR]

S11.3 Test requirements. Each plastic air brake tubing assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S12. However, a particular tubing assembly or appropriate part thereof need not meet further requirements after having met the constriction requirement (S11.3.1) and then having been subjected to any one of the requirements specified in S11.3.2 through S11.3.24. Unless otherwise specified, testing is conducted on a sample of tubing 12 inches in length.

S12.1 Air brake tubing dimensions. Measure the tubing dimensions including wall thickness, inside diameter, and outside diameter, using appropriate metrology apparatus such as micrometers, dial indicators and gauges, or optical comparators. To account for slight out-of-round conditions, diameter measurements may be calculated using the average of the major and minor diameters.

S12.2 Constriction test. Perform the constriction test in S6.12 using an air brake tubing assembly, except that the spherical diameter “A” of the plug gauge in Figure 4, or the diameter of the rigid spherical ball in S6.12.3(a), shall be 66 percent of the nominal inside diameter of the tubing as specified in Table VII.

S12.3 High temperature conditioning and dimensional stability test. (a) Condition the tubing at 230 degrees Fahrenheit (110 degrees Celsius) for 4 hours in an air oven. (b) Remove the tubing from the oven and allow to cool at room temperature for 30 minutes. (c) Measure the dimensions of the tubing using the procedure in S12.1.

S12.4 Boiling water conditioning and dimensional stability test. (a) Utilize a container constructed of a non-reactive material large enough so that the tubing to be tested does not touch any surface of the container. Fill container with distilled water. (b) Slip the tubing over a stainless steel wire for positioning it in the pot. (c) Bring the water to a boil. Place the tubing in the water and position it so that it does not touch the container. Boil the tubing for two hours. Replenish the water as necessary, adding it slowly so that the water in the pot boils continuously. (d) Remove the tubing from the water and allow to cool at room temperature for 30 minutes. Wipe off any water that remains on the tubing. [excerpt continues in the eCFR]

S12.5 Burst strength test. (a) Utilize an air brake tubing assembly or prepare a 12 inch length of tubing and install end fittings according to the end fitting manufacturer's instructions. (b) Plug one end of the assembly, fill it with water, and connect the other end to a source of water pressure. Bleed any air from the assembly and water pressure system. (c) Increase the water pressure inside the tubing assembly at a rate of 3,000 psi per minute to the burst strength pressure for the size of tubing being tested as specified in Table VIII.

S13 Test Conditions. Each hose assembly or appropriate part thereof shall be able to meet the requirements of S5, S7, S9, and S11, under the following conditions.

Test conditions and procedures as stated

These excerpts come from headings of 571.106 that cover test conditions, procedures or similar subjects.

S5.3 Test requirements. A hydraulic brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S6. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having been subjected to and having met the constriction requirement (S5.3.1) and any one of the requirements specified in S5.3.2 through S5.3.13.

S7.3 Test requirements. Each air brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S8. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having met the constriction requirement (S7.3.1) and then having been subjected to any one of the requirements specified in S7.3.2 through S7.3.13.

S9.2 Test requirements. Each vacuum brake hose assembly or appropriate part thereof shall be capable of meeting any of the requirements set forth under this heading, when tested under the conditions of S13 and the applicable procedures of S10. However, a particular hose assembly or appropriate part thereof need not meet further requirements after having met the constriction requirement (S9.2.1) and then having been subjected to any one of the requirements specified in S9.2.2 through S9.2.10.

Defined terms

The standard defines 9 terms in its definitions section. Definitions are quoted from the eCFR.

• Armor means protective material installed on a brake hose to increase the resistance of the hose or hose assembly to abrasion or impact damage.
• Brake hose means a flexible conduit, other than a vacuum tubing connector, manufactured for use in a brake system to transmit or contain the fluid pressure or vacuum used to apply force to a vehicle's brakes. For hose, a dimensional description such as “ 1/4-inch hose” refers to the nominal inside diameter. For tubing, a dimensional description such as “ 1/4-in tubing” refers to the nominal outside diameter.
• Brake hose assembly means a brake hose, with or without armor, equipped with end fittings for use in a brake system, but does not include an air or vacuum assembly prepared by the owner or operator of a used vehicle, by his employee, or by a repair facility, for installation in that used vehicle.
• Brake hose end fitting means a coupler, other than a clamp, designed for attachment to the end of a brake hose.
• Free length means the linear measurement of hose exposed between the end fittings of a hose assembly in a straight position.
• Permanently attached end fitting means an end fitting that is attached by deformation of the fitting about the hose by crimping or swaging, or an end fitting that is attached by use of a sacrificial sleeve or ferrule that requires replacement each time a hose assembly is rebuilt.
• Preformed means a brake hose that is manufactured with permanent bends and is shaped to fit a specific vehicle without further bending.
• Rupture means any failure that results in separation of a brake hose from its end fitting or in leakage.
• Vacuum tubing connector means a flexible conduit of vacuum that (i) connects metal tubing to metal tubing in a brake system, (ii) is attached without end fittings, and (iii) when installed, has an unsupported length less than the total length of those portions that cover the metal tubing.

Limits of this page

This page quotes the text of 49 CFR 571.106 as published in the eCFR, current through October 29, 2026. It omits the tables, figures, cross-referenced test procedures in other parts, and the preambles and rulemaking history that explain the rule. It does not tell you whether a given vehicle, part or product complies, how to run a test, or what a manufacturer must certify. Compliance questions go to the manufacturer's engineers, qualified counsel or NHTSA. The eCFR is an editorial compilation, not the official legal edition of the Federal Register.

Sources

Sources opened and read November 2, 2026.

• eCFR: 49 CFR 571.106, Standard No. 106; Brake hoses. (current through October 29, 2026) (read November 2, 2026)
• eCFR: 49 CFR part 571, Federal Motor Vehicle Safety Standards (current through October 29, 2026) (read November 2, 2026)