Motor carrier classes by state
South Dakota does something almost no operator expects a state to do: it grades its own counties on how hard they enforce weight law, twice a year, and it can suspend their road money for six months if the grade comes back unsatisfactory. Read that alongside the rule that voids an unsigned county ordinance outright, and you have the two halves of how weight authority actually works here.
Most of what makes an aggregate fleet hard to place has nothing to do with geography. Loading and tipping concentrate the wear into a small number of repeated motions, a great deal of the working day happens on ground that no highway rating plan was drafted against, and the hoist is usually the costliest single assembly on the unit. Those are questions about the class, and the dump trucking insurance page is where they get answered.
What South Dakota adds is a distinctive division of labor between the state and the local road authority. The weight numbers themselves are written in the code and are not unusual. What is unusual is everything built around them: an audit the Department of Transportation runs on county enforcement programs, a validity condition that can defeat a county restriction on its face, a preemption clause that protects a specific class of movement from local closure, and a construction-project exemption drawn at the activity rather than at the zone.
That matters commercially because a dump operation in South Dakota is a county-road business far more than an Interstate business. Pits, stockpiles, township grades and municipal streets are where the trucks actually run, and every one of those surfaces is controlled by a body other than the state — but under conditions the state statute writes. Knowing which conditions are conditions of validity and which are merely duties is the difference between a defensible ticket and one that should never have been written.
Every figure below is taken from the enacted South Dakota Codified Laws or the Administrative Rules of South Dakota as served by the Legislative Research Council, with the session law or rule filing that last touched it named alongside. The statute corpus read for this page is the version the Legislature publishes as effective July 29, 2026.
Running aggregate on South Dakota county and township roads? Send the counties you actually load and unload in — enforcement intensity is not uniform here, and the statute is the reason why.
SDCL 32-22-31.3, as last amended by SL 2003, ch 169, § 1, directs the secretary of the Department of Transportation to review, “not less than semi-annually,” the performance of each county’s program of overweight vehicle enforcement, and to certify a list of the counties whose programs are unsatisfactory. It is a standing audit of local enforcement effort, written into the weight chapter itself.
The statute names what the secretary weighs. Whether the county asked the Division of Highway Patrol to assist in enforcing “that county’s spring or other posted load limits.” The county’s diligence in enforcing in court, to the fullest extent possible, all fines authorized by chapter 32-22 “without plea bargaining or reducing statutory fines or civil penalties” — specifically for a second or subsequent offense by a driver within a four-year period, and for any violation of the spring restriction section. The effort of local law enforcement agencies to enforce the chapter on that county’s roads. And “such other factors as the secretary may deem appropriate” after consulting the state associations for county sheriffs, commissioners, state’s attorneys and highway superintendents, together with the Highway Patrol.
There is a procedural guard on the finding and it is worth quoting: the secretary “may not find any county’s program to be unsatisfactory unless the secretary has given the county a written specification of the county’s program deficiencies at least thirty days before the unsatisfactory certification.” Only after that does the money move. For a county certified unsatisfactory the secretary may “withhold or suspend for a period of one hundred eighty days all or any portion of any transfer of federal surface transportation funds and state funds otherwise authorized by § 32-11-35 to be distributed to such county.” The Department of Revenue is directed to cooperate in administering the section.
The practical reading for a carrier is straightforward. A South Dakota county has a direct financial reason not to be lenient on an overweight aggregate truck, not to reduce a second-offense fine, and not to leave a spring posting unenforced. Plea bargaining is not just discouraged, it is a named audit factor. An operator whose loss history includes a pattern of weight citations should expect those citations to survive rather than soften, and should expect the pattern to be visible.
SDCL 32-14-6, last amended by SL 2002, ch 158, § 3, is the grant of local weight authority, and it fences the grant three separate ways. Local authorities, including road districts, “may by ordinance or resolution prohibit the operation of vehicles upon any highway or impose restrictions as to the weight of vehicles allowed.” That is the power.
The first fence is jurisdictional. The prohibition or restriction applies “only to vehicles to be operated upon any highway under the jurisdiction of and for the maintenance of which such local authorities are responsible.” The second is substantive and is the one operators most often do not know about: the restriction is permitted “only if the highway by reason of physical condition, rain, snow, or other climatic conditions will be seriously damaged or destroyed unless the use of vehicles on the highway is prohibited or the permissible weights of the vehicles are reduced.” The statutory trigger is physical damage to the road. It is not convenience, not traffic preference, and not revenue.
The third fence is the sharpest sentence in the section. The enacting authority “shall erect and maintain or cause to be erected and maintained signs designating the provisions of the ordinance or resolution at each end of that portion of any highway affected” — and then: “The ordinance or resolution is not valid unless such signs are erected and maintained.” The signage is not an implementation duty attached to a valid rule. It is a condition of the rule’s validity, stated on the face of the statute, in the present tense, tied to maintenance as well as erection.
A parallel power over vehicle class sits immediately alongside at SDCL 32-14-7 (SL 1999, ch 151, § 7), letting local authorities prohibit trucks or other commercial vehicles or impose weight limitations “on designated highways,” with the prohibitions and limitations “designated by appropriate signs placed on such highways.”
For a hauler the operational consequence is that the sign at the end of the affected segment is the legal instrument you are actually being measured against, and a photograph of its absence is worth more than any records request. For anyone underwriting the account, it means a South Dakota weight citation on a local road has a defense that does not exist in most places, and that a claim file which never asked the question has left something on the table.
SDCL 32-22-8.2, last touched by SL 1992, ch 372, § 17, carries a preemption clause: “No local unit of government may deny commercial motor vehicle combinations described in § 32-22-8.1 or motor vehicles operating under a special permit access to the interstate system or state trunk system highways from established truck terminals, loading docks, or maintenance facilities.”
Read the scope carefully, because it is narrower than the headline suggests and the narrowing is the useful part. The shield does not attach to every truck. It attaches to two identified classes: the combinations described in SDCL 32-22-8.1 — the length classes, including the truck tractor and semitrailer combination and the straight truck and trailer combination — and any motor vehicle “operating under a special permit.” A permitted overweight movement is inside the protection by the second limb regardless of configuration. An unpermitted solo straight truck is not obviously inside either.
The same section gives the Division of Highway Patrol power to grant access permits to those vehicles to reach any established truck terminal, loading dock or maintenance facility, and requires that “The access permit shall state the highway or street to be traveled upon and shall be available at all permit locations in the state.” The access instrument is route-specific and publicly obtainable, which is what makes it usable at short notice.
The commercial point is that South Dakota has drawn a line exactly where an aggregate operation is most exposed — the connection between a yard, a dock or a maintenance shop and the state system. A local body may close a road against physical damage under 32-14-6, but it may not use that power to sever this particular connection for the protected classes. For a fleet whose terminal sits on a municipal street, that distinction is worth confirming before the first spring posting rather than after it.
Working South Dakota county roads through the spring window? Tell us which counties and which pits, and we will build the program around where the trucks actually run.
SDCL 32-22-16, “Maximum weight of vehicle or combination of vehicles — Axles — Misdemeanor,” last amended by SL 1996, ch 205, § 1, states the limits. No vehicle or combination on a public highway may have a weight in excess of twenty thousand pounds on any one axle, or in excess of the tire weight per inch of tire width prescribed by § 32-22-21, “including all enforcement tolerances.” Nor in excess of thirty-four thousand pounds on any tandem axle, subject to the same tire alternative and the same tolerance language. Nor in excess of the maximum on two or more consecutive axles determined by the formula in § 32-22-16.1, again subject to the tire figure.
Two further provisions sit in the same section. A hard ceiling: “However, in no instance may the gross weight of any vehicle or combination of vehicles exceed eighty thousand pounds on the interstate highway.” And a spacing allowance, in the section’s own words: “Two consecutive sets of tandem axles may carry a gross load of thirty-four thousand pounds each provided the overall distance between the first and last axles of such consecutive sets of tandem axles is thirty-six feet or more.” A violation of the section is a Class 2 misdemeanor. SDCL 32-22-16.1 (SL 1985, ch 15, § 40) supplies the formula itself, W = 500 [LN/(N-1) + 12N + 36], computed to the nearest five hundred pounds.
The structural feature worth understanding is that each limb of 32-22-16 is written as an axle figure or a tire figure, whichever is exceeded first. The tire schedule is not a footnote to the axle table; it is stated as an equal alternative ceiling. And SDCL 32-22-21 closes the loop from the other direction — “In no instance may the weight on any axle or combination of axles exceed the maximum weight limits specified in § 32-22-16.” Each caps the other, and the lower of the two governs the load.
That tire schedule, as amended by SL 2026, ch 137, § 1, runs at five hundred pounds per inch of tire width on any ordinary axle, and six hundred pounds per inch on an axle equipped with dual tires, on a steering axle, on a trailer axle where the towing vehicle has a gross vehicle weight rating of eleven thousand pounds or less, and on an axle equipped with tires at least four hundred forty-five millimeters or seventeen and one-half inches wide when operated on a highway identified in § 32-22-21.2. A mobile crane axle operating under a § 32-22-42 permit with the boom carried over the vehicle takes six hundred fifty. Tire width, under SDCL 32-22-22, means “the diameter of the cross-section of such tires as customarily measured and rated by the manufacturers of motor vehicles and tires.”
SDCL 32-22-21.2 (SL 2013, ch 148, § 2) fixes that highway list at eight items: the interstate highway system; any locally designated highway within the corporate limits of a municipality adjacent to the interstate system; U.S. Highway 12 from Interstate 29 to Aberdeen; State Highway 37 from Interstate 90 to Huron; U.S. Highway 83 from Interstate 90 to Pierre; State Highway 79 from Interstate 90 to the Nebraska border; U.S. Highway 85 from Interstate 90 to Belle Fourche; and State Highway 50 from Interstate 29 to Yankton. A wide-base-equipped truck therefore carries a different lawful axle weight depending on which road it is standing on — which is a routing question, not an equipment question, and one that belongs in a dispatch conversation rather than in a driver’s memory.
SDCL 32-22-24, last amended by SL 2002, ch 158, § 1, opens by making the reduction mandatory rather than discretionary: “The maximum axle and axle group loadings as set forth in § 32-22-16 shall be reduced during the period of each year from February fifteenth to April thirtieth, inclusive.” The proper highway authority responsible for maintenance sets the reduced limits during that period and “may increase, lessen, or remove these restrictions if highway conditions warrant.” The discretion runs to how much, not to whether.
Two features of the section change how an operator has to find out what the limit is. First, formality is optional: “That authority may be exercised without formal resolution if the highway authority erects or causes to be erected and maintained signs designating the restrictions.” A search of published county resolutions is therefore not a reliable way to learn a spring limit, because a valid restriction may never have been reduced to one. Second, the calendar is a floor rather than a ceiling: “If highway and climatic conditions warrant, the proper highway authority may extend the time period mentioned in this section by ordinance or resolution.” The extension, unlike the imposition, does require the instrument.
The section preserves the parallel restriction powers rather than displacing them, naming §§ 32-14-6, 32-14-7 and 32-22-25 in terms. It also carries the relief valve: during the same period the transportation commission may, under § 32-22-42, allow the issuance of overweight permits to heavier vehicles on “those highways which the commission designates as capable of handling heavier loads.” A violation of the section is a Class 2 misdemeanor — and, as noted above, is one of the two categories the county enforcement audit specifically asks about.
SDCL 32-22-25 (SL 2002, ch 158, § 2) supplies the non-seasonal version of the same power and names the bodies that hold it: the Department of Transportation, “the board of county commissioners of any county, the board of supervisors of any township, or the board of trustees of any road district,” where highways would be damaged or destroyed by heavy traffic “by reason of thawing or excessive moisture, or for any reason.” Notice is by signs of substantial construction at each end of the reduced section and at points of intersection, “as deemed necessary by the proper highway authority.”
For scheduling and for coverage alike, the takeaway is that South Dakota’s spring window has a published start and end that neither guarantees a restriction on any given road nor caps how late one may run. Contracts written on an assumption that hauling resumes on May 1 are written on the statutory floor, not on the statute.
SDCL 32-22-30.1, added by SL 1972, ch 180, is short enough to quote whole: “Notwithstanding the provisions of this chapter, the Department of Transportation or county commissioners may permit public and private vehicles and equipment in excess of the weight limitations established in this chapter to be operated on highway construction projects on public highways under their respective jurisdictions while said highway projects are under construction.”
Three things in that sentence carry real weight for a contract hauler. The relief runs against the whole chapter, so it reaches the axle table, the tire schedule and the spring reduction alike. It covers private vehicles and equipment, not only agency plant, so a contractor’s own trucks are within its reach. And the granting authority is split on jurisdictional lines — the Department for state highways, county commissioners for county highways, each “under their respective jurisdictions” — which makes this as much a delegation as an exemption, and means the right conversation is with the body that owns the road the project sits on.
The broader exemption lives one chapter over and draws the line that an aggregate operation crosses several times a day. SDCL 32-14-8 (SL 1989, ch 256, § 12) provides that the named size, weight and equipment chapters “do not apply to persons, teams, motor vehicles, and other equipment while actually engaged in work upon the surface of a highway, but shall apply to such persons and vehicles when traveling to or from such work.”
The exemption is keyed to the activity, not to the zone and not to the plate. A truck placing material on the highway surface is outside those chapters; the same truck running back to the pit for the next load is inside them. There is no geographic buffer, no project-boundary allowance and no cone-to-cone rule in the text. Anyone building a haul cycle around a resurfacing job should assume the legal status of the vehicle changes at the moment the work stops, and should not assume a project sign converts a public road into a work area for weight purposes.
Enforcement of the exempt population is handled by paperwork rather than by the scale. SDCL 32-22-31.2 (SL 2004, ch 17, § 141) lets any county highway superintendent or municipal street superintendent inspect any scale ticket issued by any weight scale operator for a vehicle “being used in connection with removal of construction aggregate from a county-permitted gravel pit” or for public highway work under a county, township or municipal contract, with any violation reported to the Department of Public Safety. SDCL 32-22-31.1 gives the Department of Transportation the same power for contracts it administers. The scale ticket is a record the state has an express statutory right to read — which is worth knowing before deciding how long to keep them.
The permit rulebook is ARSD Article 70:03, “Oversize, Overweight Vehicles,” promulgated under SDCL 32-22-42. It carries a financial-responsibility condition that appears in neither the statute nor the state’s driver-facing handbook. ARSD 70:03:01:11, in the form effective July 1, 1987, provides that applicants “must carry public liability insurance in the amount of at least $100,000 per person and $300,000 per accident and $100,000 property damage, or qualify as a self insurer pursuant to SDCL 32-35-90.”
The self-insurance alternative has a size gate. SDCL 32-35-90 permits a certificate of self-insurance only where more than twenty-five vehicles are registered in the applicant’s name in this state. A fleet at or below that count has no self-insurance route to a South Dakota oversize or overweight permit and must show the policy. Those published minimums are a permit condition rather than a limit anyone should stop at — they sit far below the exposure an aggregate combination actually generates, and the gap between them is the ordinary subject of a trucking auto liability conversation.
The permit also transfers nothing. ARSD 70:03:01:12 states that issuance “does not relieve the permit holder from liability for damages caused to any person or property either on the traveled portion of the highway or the right-of-way,” and its statutory twin at SDCL 32-22-43 (SL 2010, ch 145, § 185) says the same for damage to the highway. Where the damage is to a posted bridge, SDCL 32-22-48 makes the operator liable to the county, township or the State in a civil action for the injury sustained, with the violation itself a Class 2 misdemeanor. Recovery runs through litigation, so the exposure lands where a general liability and auto liability program has to answer for it rather than against a sum posted in advance.
Pricing is in the rule as well. ARSD 70:03:01:02, last amended effective September 6, 2004, sets the fee for an individual single-trip permit at $25 and a book of ten self-issuing single-trip permits at $250, and adds, for an overweight vehicle, “an additional fee of two cents for each ton or fraction of a ton that its gross weight exceeds the following weight limits, for each mile traveled on state trunk highways,” subject to a floor of one dollar. The thresholds are stated by axle count: two axles, 40,000 pounds; three, 60,000; four, 80,000; five, 85,000; six, 90,000; seven or more, 95,000. State agencies, local subdivisions of this or a foreign state, and federal agencies are exempt from both the permit fee and the ton-mile fee.
The rest of the article shapes how the instrument behaves. Issuance is discretionary under 70:03:01:05 — “An application for a permit does not assure permit approval.” Overweight permits issue only after route approval by the Department of Transportation, Division of Operations, or its designee, under 70:03:01:17. The route may be designated by the issuing authority under 70:03:01:10. The permit must be carried in the permit vehicle and produced on request under 70:03:01:06, which also lets an enforcement authority revoke it for a violation of its terms, with the effect on the driver being “the same as operating without a permit.” Only single-trip permits issue for overweight loads on the interstate system at all, under 70:03:01:08.
For a distance-priced structure like this one, the cost of a movement is a function of tons over the threshold multiplied by miles, so routing and load planning drive the number more than the permit itself does. Operators who regularly need capacity beyond the ordinary schedule should look at how that work is structured on the oversized and overweight trucking insurance page before treating it as an incidental part of an aggregate contract.
SDCL 32-15-18, “Improperly loaded vehicle unlawful — Violation as misdemeanor,” sourced to SDC 1939, § 44.0350 and last touched by SL 1989, ch 255, § 34, states the whole duty in one sentence: “No person may drive or move any vehicle on any highway unless such vehicle is so constructed or loaded as to prevent its contents from dropping, sifting, leaking, or otherwise escaping therefrom.” A violation is a Class 2 misdemeanor.
There is no covering term anywhere in the text — no tarpaulin, no cover, no securement device — and the operator is given two alternative routes to compliance on the face of the statute: so constructed, or so loaded. South Dakota states the rule as an outcome to be achieved rather than as equipment to be fitted, and the section is old and stable rather than a recent policy turn.
A performance standard shifts the burden in a specific direction. Compliance cannot be demonstrated by an inspection at rest, because there is nothing prescribed to inspect; it is demonstrated by the load not escaping in transit. That makes body condition, tailgate seal, load height and the discipline of how a pit loads the truck into evidence rather than into housekeeping. Windshield and paint claims from escaping stone are a recurring third-party exposure in this class, and in a state with no covering mandate the defense is the loading practice itself.
The insurance consequence follows the same line. An operator who runs uncovered is lawful here, and is also carrying the whole of the escape risk on its own procedures. Where those procedures are documented, they support the account. Where they are not, a run of small third-party property claims tends to arrive without anything to explain it — which is a physical damage and liability story that gets told at renewal whether or not anyone chose to tell it.
South Dakota regulates aggregate extraction in its own chapter, SDCL ch. 45-6, “Sand, Gravel and Construction Aggregate Mining.” Under SDCL 45-6-65, last amended by SL 2024, ch 181, § 1, a license is required to mine sand, gravel, rock to be crushed and used in construction, and the other listed materials, and “The fee for the license is one hundred dollars annually, for each mine site authorized under the license.” Compliance is measured per site: “Failure to comply with these requirements for each site mined constitutes mining without a license.”
The security is at the pit rather than on the road, and it is on a schedule that steps up. SDCL 45-6-71, as amended by SL 2024, ch 181, § 2, requires an operator to submit a surety to the department before mining commences. For an operation licensed before July 1, 2024, the amount runs at five hundred dollars per acre of affected land or twenty thousand dollars statewide through June 30, 2026; one thousand five hundred dollars per acre or one hundred thousand dollars statewide from July 1, 2026 through June 30, 2027; two thousand seven hundred fifty dollars per acre or two hundred thousand dollars statewide from July 1, 2027 through June 30, 2029; and three thousand eight hundred fifty dollars per acre or three hundred thousand dollars statewide from July 1, 2029. An operation licensed on or after July 1, 2024 pays the top figure from the outset. On the date this page reads the statute, the operative band for a pre-2024 licensee is the one thousand five hundred dollar per acre and one hundred thousand dollar statewide tier.
The statute permits alternatives in place of the surety — an irrevocable letter of credit, a cash deposit, a certificate of deposit made payable to the board, or government securities — and where a corporate surety bond is used it must be signed by the operator as principal and by a surety insurer certified under chapter 58-21. The surety “must remain in effect until the affected land has been reclaimed, the reclamation is approved by the board, and the surety is released by the board.”
For a vertically integrated operation that both mines and hauls, this is the part of the balance sheet that is easiest to underestimate, because the obligation is open-ended in time rather than annual. It also sits alongside, not inside, the highway regime — nothing in chapter 45-6 confers an aggregate-specific weight allowance, a designated corridor or a commodity-based permit class. On the road, an aggregate hauler in South Dakota is governed by the same axle table, tire schedule and spring window as everyone else.
The state minimum is a licensing threshold. The program an operator actually needs is built from these lines:
We write dump and aggregate hauling as a named class rather than as an exception to general trucking, and we read each account against the weight and permit regime of the state it operates in. For a South Dakota operator that means starting from what the trucks are actually licensed and configured to carry, sizing physical damage to bodies and hoists rather than to a chassis value, and treating pit, stockpile and job-site work as its own exposure rather than an extension of the highway auto form.
If the operation also runs freight under separate authority, the South Dakota trucking insurance page covers the state’s broader motor carrier picture, and the dump trucking insurance page covers the class mechanics that apply wherever the operator runs.
It can act without a formal resolution during the February 15 to April 30 window, but not without signs. SDCL 32-22-24 lets the highway authority exercise the seasonal power “without formal resolution if the highway authority erects or causes to be erected and maintained signs designating the restrictions.” Outside that mechanism, SDCL 32-14-6 requires signs at each end of the affected portion and provides that the ordinance or resolution “is not valid unless such signs are erected and maintained.” The sign is what you are legally on notice of.
No covering is prescribed. SDCL 32-15-18 requires that a vehicle be “so constructed or loaded as to prevent its contents from dropping, sifting, leaking, or otherwise escaping therefrom,” and a violation is a Class 2 misdemeanor. The statute names no tarpaulin, cover or securement device and gives two alternative routes to compliance. That makes it a standard about the outcome rather than about equipment, so an uncovered load is lawful only for as long as nothing leaves it.
The cost is driven by the ton-mile charge rather than by the permit. Under ARSD 70:03:01:02, an individual single-trip permit is $25 and a book of ten self-issuing permits is $250. An overweight vehicle then pays two cents for each ton or fraction of a ton by which gross weight exceeds the axle-count threshold, for each mile traveled on state trunk highways, with a one-dollar floor. The thresholds are 40,000 pounds on two axles, 60,000 on three, 80,000 on four, 85,000 on five, 90,000 on six, and 95,000 on seven or more. Because miles are a multiplier, a long haul and a short haul at the same weight are priced very differently.
Only while it is actually working on the highway surface. SDCL 32-14-8 disapplies the size, weight and equipment chapters to vehicles “while actually engaged in work upon the surface of a highway,” but expressly applies them “when traveling to or from such work.” Separately, SDCL 32-22-30.1 lets the Department of Transportation or county commissioners permit public and private vehicles over the chapter’s weight limits on projects under construction within their respective jurisdictions. The first is automatic and narrow; the second requires the road authority to grant it.
Because the state audits them for it. SDCL 32-22-31.3 requires the secretary of the Department of Transportation to review each county’s overweight enforcement program not less than semi-annually and to certify those that are unsatisfactory, weighing whether the county sought Highway Patrol assistance with its posted load limits and how diligently it enforced fines in court “without plea bargaining or reducing statutory fines or civil penalties.” A county certified unsatisfactory can have federal surface transportation and state funds withheld or suspended for one hundred eighty days.
Not against the classes SDCL 32-22-8.2 protects. That section bars any local unit of government from denying the combinations described in SDCL 32-22-8.1, or any motor vehicle operating under a special permit, access to the interstate or state trunk system “from established truck terminals, loading docks, or maintenance facilities.” The Division of Highway Patrol may also grant an access permit naming the highway or street to be traveled. Note the scope: the protection attaches to those combination classes and to permitted movements, not to every vehicle in the fleet.
Every figure on this page was read at the source below on August 11, 2026, with the effective date of the version read. Treat each as current as of that date rather than as permanent.
Send the declared or registered weights alongside the axle configurations, and tell us where the material moves from. We will size the program against the work the trucks actually do rather than against a statutory floor.
