§FMCSR.com
Historical textIn force on Oct. 1, 2003Source: annual CFR editions 1996–2004

§ 393.42 Brakes required on all wheels.

Wording first on file in the 1996 annual edition, superseded by the 2005 annual edition.

govinfo, 2003 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2003 edition's wording. An amendment that took effect between Oct. 1, 2003 and Oct. 1, 2003 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 393.42 — Brakes required on all wheels.. Text in force on October 1, 2003. This wording effective October 1, 1996 to October 1, 2005. Source: govinfo, 2003 edition, https://www.govinfo.gov/app/details/CFR-2003-title49-vol4/CFR-2003-title49-vol4-sec393-42. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.42?asof=2003-10-01, on October 26, 2026. Unofficial compilation; verify against the official source.

(a) Every commercial motor vehicle shall be equipped with brakes acting on all wheels.

(b) Exception. (1) Trucks or truck tractors having three or more axles—

(i) Need not have brakes on the front wheels if the vehicle was manufactured before July 25, 1980; or

(ii) Manufactured between July 24, 1980, and October 27, 1986, must be retrofitted to meet the requirements of this section within one year from February 26, 1987, if the brake components have been removed.

(2) Any motor vehicle being towed in a driveaway-towaway operation must have operative brakes as may be necessary to ensure compliance with the performance requirements of § 393.52. This paragraph is not applicable to any motor vehicle towed by means of a tow-bar when any other vehicle is full-mounted on such towed motor vehicle or any combination of motor vehicles utilizing three or more saddle-mounts. (See § 393.71(a)(3).)

(3) Any full trailer, any semitrailer, or any pole trailer having a GVWR of 3,000 pounds or less must be equipped with brakes if the weight of the towed vehicle resting on the towing vehicle exceeds 40 percent of the GVWR of the towing vehicle.

[Figure or graphic omitted. See the official source.]

[52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996]

Amendment history

6 distinct wordings on file since Oct. 1, 1996
  1. March 23, 2026 → presenteCFR, day-precisediff vs. previous
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005; 76 FR 56321, Sept. 13, 2011; 91 FR 7890, Feb. 19, 2026]
  2. Feb. 19, 2026 → March 23, 2026eCFR, day-precisediff vs. previous
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005; 76 FR 56321, Sept. 13, 2011]
  3. Oct. 1, 2012 → Feb. 19, 2026annual editions 2012–2016diff vs. previous
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005; 76 FR 56321, Sept. 13, 2011]
  4. Oct. 1, 2011 → Oct. 1, 2012annual edition 2011diff vs. previous
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005]
  5. Oct. 1, 2005 → Oct. 1, 2011annual editions 2005–2010diff vs. previous
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996; 70 FR 48049, Aug. 15, 2005]
  6. Oct. 1, 1996 → Oct. 1, 2005annual editions 1996–2004viewing
    [52 FR 2803, Jan. 27, 1987, as amended at 53 FR 49398, Dec. 7, 1988; 54 FR 48617, Nov. 24, 1989; 59 FR 25574, May 17, 1994; 61 FR 1843, Jan. 24, 1996]

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.