---
kind: "section"
citation: "49 C.F.R. § 393.52"
title: "49"
number: "393.52"
heading: "Brake performance."
url: "https://uscodex.org/cfr/49/393.52"
---

# §393.52. Brake performance.

- (a) Upon application of its service brakes, a motor vehicle or combination of motor vehicles must under any condition of loading in which it is found on a public highway, be capable of—
  - (1) Developing a braking force at least equal to the percentage of its gross weight specified in the table in [paragraph (d)](#d) of this section;
  - (2) Decelerating to a stop from 20 miles per hour at not less than the rate specified in the table in [paragraph (d)](#d) of this section; and
  - (3) Stopping from 20 miles per hour in a distance, measured from the point at which movement of the service brake pedal or control begins, that is not greater than the distance specified in the table in [paragraph (d)](#d) of this section; or, for motor vehicles or motor vehicle combinations that have a GVWR or GVW greater than 4,536 kg (10,000 pounds),
  - (4) Developing only the braking force specified in [paragraph (a)(1)](#a-1) of this section and the stopping distance specified in [paragraph (a)(3)](#a-3) of this section, if braking force is measured by a performance-based brake tester which meets the requirements of functional specifications for performance-based brake testers for commercial motor vehicles, where braking force is the sum of the braking force at each wheel of the vehicle or vehicle combination as a percentage of gross vehicle or combination weight.
- (b) Upon application of its emergency brake system and with no other brake system applied, a motor vehicle or combination of motor vehicles must, under any condition of loading in which it is found on a public highway, be capable of stopping from 20 miles per hour in a distance, measured from the point at which movement of the emergency brake control begins, that is not greater than the distance specified in the table in [paragraph (d)](#d) of this section.
- (c) Conformity to the stopping-distance requirements of paragraphs [(a)](#a) and [(b)](#b) of this section shall be determined under the following conditions:
  - (1) Any test must be made with the vehicle on a hard surface that is substantially level, dry, smooth, and free of loose material.
  - (2) The vehicle must be in the center of a 12-foot-wide lane when the test begins and must not deviate from that lane during the test.
- (d) **Vehicle brake performance table—**

## Notes

### Amendments

[36 FR 20298, Oct. 20, 1971, as amended at 37 FR 5251, Mar. 11, 1972; 37 FR 11336, June 7, 1972; 67 FR 51777, Aug. 9, 2002]

### Authority

Authority: 49 U.S.C. 31136, 31151, 31502; sec. 1041(b), Pub. L. 102-240, 105 Stat. 1914, 1993; secs. 5301 and 5524, Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; and 49 CFR 1.87.

### Source

Source: 33 FR 19735, Dec. 25, 1968, unless otherwise noted.

### Amendments

[36 FR 20298, Oct. 20, 1971, as amended at 37 FR 5251, Mar. 11, 1972; 37 FR 11336, June 7, 1972; 67 FR 51777, Aug. 9, 2002]