§FMCSR.com
Historical textIn force on Oct. 1, 2005Source: annual CFR editions 2005–2010

§ 393.42 Brakes required on all wheels.

Wording in the annual edition revised as of Oct. 1, 2005, superseded by the 2011 annual edition.

govinfo, 2005 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2005 edition's wording. An amendment that took effect between Oct. 1, 2005 and Oct. 1, 2005 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
What changedOct. 1, 1996 wording → Oct. 1, 2005 wording+243 added−88 removedHide

(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) Needand not have brakes on the front wheels if the vehicle was manufactured before July 25, 1980;, or
(ii)are Manufacturednot betweenrequired Julyto 24,have 1980,brakes andon Octoberthe 27,front 1986wheels. However, mustthese bevehicles retrofittedmust to meet the requirements of this§ section within one year from February 26, 1987, if the brake components have been removed393.52.
(2) AnyMotor motorvehicles vehicle being towed in a driveaway-towaway operation mustare not required to have operative brakes asprovided maythe becombination necessaryof tovehicles ensuremeets compliance with the performance requirements of § 393.52. This paragraphexception is not applicable to:
(i) anyAny motor vehicle towed by means of a tow-bar when anyanother othermotor vehicle is full-mounted on suchthe towed motor vehicle; orand
(ii) anyAny combination of motor vehicles utilizing three or more saddle-mounts.
(See3) §Any 393.71semitrailer or pole trailer (aladen or unladen) with a gross weight of 1,361 kg (3,000 pounds) or less which is subject to this part is not required to be equipped with brakes if the axle weight of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle.)
(34) Any full trailer, any semitrailer, or anyfour-wheel pole trailer having(laden or unladen) with a GVWRgross weight of 1,361 kg (3,000 pounds) or less mustwhich is subject to this part is not required to be equipped with brakes if the weightsum of the axle weights of the towed vehicle restingdoes onnot exceed 40 percent of the sum of the axle weights of the towing vehicle.
(5) exceedsBrakes 40are percentnot required on the steering axle of a three-axle dolly which is steered by a co-driver.
(6) Loaded housemoving dollies, specialized trailers and dollies used to transport industrial furnaces, reactors, and similar motor vehicles are not required to be equipped with brakes, provided the GVWRspeed at which the combination of vehicles will be operated does not exceed 32 km/hour (20 mph) and brakes on the towingcombination of vehicles are capable of stopping the combination within 12.2 meters (40 feet) from the speed at which the vehicle is being operated or 32 km/hour (20 mph), whichever is less.
[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; 70 FR 48049, Aug. 15, 2005]

49 CFR § 393.42 — Brakes required on all wheels.. Text in force on October 1, 2005. This wording effective October 1, 2005 to October 1, 2011. Source: govinfo, 2005 edition, https://www.govinfo.gov/app/details/CFR-2005-title49-vol5/CFR-2005-title49-vol5-sec393-42. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.42?asof=2005-10-01, 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 and manufactured before July 25, 1980, are not required to have brakes on the front wheels. However, these vehicles must meet the requirements of § 393.52.

(2) Motor vehicles being towed in a driveaway-towaway operation are not required to have operative brakes provided the combination of vehicles meets the requirements of § 393.52. This exception is not applicable to:

(i) Any motor vehicle towed by means of a tow-bar when another motor vehicle is full-mounted on the towed vehicle; and

(ii) Any combination of motor vehicles utilizing three or more saddle-mounts.

(3) Any semitrailer or pole trailer (laden or unladen) with a gross weight of 1,361 kg (3,000 pounds) or less which is subject to this part is not required to be equipped with brakes if the axle weight of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle.

(4) Any full trailer or four-wheel pole trailer (laden or unladen) with a gross weight of 1,361 kg (3,000 pounds) or less which is subject to this part is not required to be equipped with brakes if the sum of the axle weights of the towed vehicle does not exceed 40 percent of the sum of the axle weights of the towing vehicle.

(5) Brakes are not required on the steering axle of a three-axle dolly which is steered by a co-driver.

(6) Loaded housemoving dollies, specialized trailers and dollies used to transport industrial furnaces, reactors, and similar motor vehicles are not required to be equipped with brakes, provided the speed at which the combination of vehicles will be operated does not exceed 32 km/hour (20 mph) and brakes on the combination of vehicles are capable of stopping the combination within 12.2 meters (40 feet) from the speed at which the vehicle is being operated or 32 km/hour (20 mph), whichever is less.

[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; 70 FR 48049, Aug. 15, 2005]

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. previousviewing
    [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 1996–2004
    [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.