[Code of Federal Regulations]
[Title 23, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 23CFR658.17]

[Page 285-287]
 
                           TITLE 23--HIGHWAYS
 
 CHAPTER I--FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 658_TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS_LENGTH, WIDTH AND 
 
Sec.  658.17  Weight.

    (a) The provisions of the section are applicable to the National 
System of Interstate and Defense Highways and reasonable access thereto.
    (b) The maximum gross vehicle weight shall be 80,000 pounds except 
where lower gross vehicle weight is dictated by the bridge formula.
    (c) The maximum gross weight upon any one axle, including any one 
axle of a group of axles, or a vehicle is 20,000 pounds.
    (d) The maximum gross weight on tandem axles is 34,000 pounds.

[[Page 286]]

    (e) No vehicle or combination of vehicles shall be moved or operated 
on any Interstate highway when the gross weight on two or more 
consecutive axles exceeds the limitations prescribed by the following 
formula, referred to as the Bridge Gross Weight Formula:
[GRAPHIC] [TIFF OMITTED] TC14OC91.012


except that two consecutive sets of tandem axles may carry a gross load 
of 34,000 pounds each if the overall distance between the first and last 
axle is 36 feet or more. In no case shall the total gross weight of a 
vehicle exceed 80,000 pounds.
    (f) Except as provided herein, States may not enforce on the 
Interstate System vehicle weight limits of less than 20,000 pounds on a 
single axle, 34,000 pounds on a tandem axle, or the weights derived from 
the Bridge Formula, up to a maximum of 80,000 pounds, including all 
enforcement tolerances. States may not limit tire loads to less than 500 
pounds per inch of tire or tread width, except that such limits may not 
be applied to tires on the steering axle. States may not limit steering 
axle weights to less than 20,000 pounds or the axle rating established 
by the manufacturer, whichever is lower.
    (g) The weights in paragraphs (b), (c), (d), and (e) of this section 
shall be inclusive of all tolerances, enforcement or otherwise, with the 
exception of a scale allowance factor when using portable scales (wheel-
load weighers). The current accuracy of such scales is generally within 
2 or 3 percent of actual weight, but in no case shall an allowance in 
excess of 5 percent be applied. Penalty or fine schedules which impose 
no fine up to a specified threshold, i.e., 1,000 pounds, will be 
considered as tolerance provisions not authorized by 23 U.S.C. 127.
    (h) States may issue special permits without regard to the axle, 
gross, or Federal Bridge Formula requirements for nondivisible vehicles 
or loads.
    (i) The provisions of paragraphs (b), (c), and (d) of this section 
shall not apply to single-, or tandem-axle weights, or gross weights 
legally authorized under State law on July 1, 1956. The group of axles 
requirement established in this section shall not apply to vehicles 
legally grandfathered under State groups of axles tables or formulas on 
January 4, 1975. Grandfathered weight limits are vested on the date 
specified by Congress and remain available to a State even if it chooses 
to adopt a lower weight limit for a time.
    (j) The provisions of paragraphs (c) through (e) of this section 
shall not apply to the operation on Interstate Route 68 in Allegany and 
Garrett Counties, Maryland, of any specialized vehicle equipped with a 
steering axle and a tridem axle and used for hauling coal, logs, and 
pulpwood if such vehicle is of a type of vehicle as was operating in 
such counties on U.S. Routes 40 or 48 for such purposes on August 1, 
1991.
    (k) Any over-the-road bus, or any vehicle which is regularly and 
exclusively used as an intrastate public agency transit passenger bus, 
is excluded from the axle weight limits in paragraphs (c) through (e) of 
this section until October 1, 2009. Any State that has enforced, in the 
period beginning October 6, 1992, and ending November 30, 2005, a single 
axle weight limitation of 20,000 pounds or greater but less than 24,000 
pounds may not enforce a single axle weight limit on these vehicles of 
less than 24,000 lbs.
    (m) The provisions of paragraphs (b) through (e) of this section 
shall not apply to the operation, on I-99 between Bedford and Bald 
Eagle, Pennsylvania, of any vehicle that could legally operate on this 
highway section before December 29, 1995.
    (n) Any vehicle subject to this subpart that utilizes an auxiliary 
power or idle reduction technology unit in order to promote reduction of 
fuel use and emissions because of engine idling, may be allowed up to an 
additional 400 lbs. total in gross, axle, tandem, or bridge formula 
weight limits.
    (1) To be eligible for this exception, the operator of the vehicle 
must be able to prove:
    (i) By written certification, the weight of the APU; and
    (ii) By demonstration or certification, that the idle reduction 
technology is fully functional at all times.

[[Page 287]]

    (2) Certification of the weight of the APU must be available to law 
enforcement officers if the vehicle is found in violation of applicable 
weight laws. The additional weight allowed cannot exceed 400 lbs. or the 
weight certified, whichever is less.

[49 FR 23315, June 5, 1984, as amended at 59 FR 30420, June 13, 1994; 60 
FR 15214, Mar. 22, 1995; 62 FR 10181, Mar. 5, 1997; 63 FR 70653, Dec. 
22, 1998; 72 FR 7748, Feb. 20, 2007]