Vehicle Size and Weight Requirements for IRP
The International Registration Plan or IRP is an agreement between the US, the District of Columbia and Canadian provinces. This plan lets your truck run legally across state lines with just one plate and one set of registration fees.
IRP makes trucking between states easier and more organized, but there is a catch. The size and weight of your truck have a direct impact on how registration works, how much it costs and what permits you might need. Knowing all these things will help you stay safe and avoid getting in trouble on the road.
Vehicle Weight Requirements Under IRP
The International Registration Plan makes it possible for trucks to operate across multiple states and Canadian provinces with one license plate and one registration record. However, IRP itself does not have legal road weight limits; it uses only what you declare as your gross vehicle weight for calculating fees, eligibility and what appears on your cab card.
Federal and state laws, like the Federal Bridge Formula, axle spacing limits and the maximum gross or axle weights allowed in each state still apply to actual weight enforcement on the road.
Knowing how weight affects your IRP registration can help you avoid fines, audits and costs you didn't expect.
Gross Vehicle Weight (GVW) Thresholds for IRP Registration
Not every vehicle needs IRP registration. The rule depends on how heavy the truck or combination is and if it travels in two or more states.
Heavier and multi-axle trucks that operate between state borders must register under IRP, while smaller or intrastate ones usually don’t.
Here’s how the categories break down:
| Category | GVW | IRP Registration Status | Applies to |
| Required | Over 26,000 lbs (11,793 kg) | Required for interstate operations (two or more states) |
|
| Optional | 26,000 lbs or less | Permitted but not required |
|
| Exception | Intrastate-only, government-owned RVs or restricted-use plates (e.g., farm, dealer) | Not qualified for IRP | These vehicles don’t get plates. |
Vehicle Classifications and Weight Applications
IRP registration rules depend on vehicle type, assembly and total weight. There's a difference between a single straight truck, a tractor-trailer combo and a light pickup with a trailer.
Below is how IRP applies to different setups:
| Vehicle Type | How is weight used for IRP? | Example |
| Straight truck or box | Uses the GVW (the total loaded weight) | A 2-axle straight truck with a gross vehicle weight (GVW) of 33,000 pounds that travels between Georgia and Alabama must register with the International Registration Plan (IRP). |
| Combination Vehicle (tractor + trailer) | Uses the CGW, combining tractor and trailer weights | A tractor that weighs 12,000 pounds and pulls a loaded 53-foot trailer that weighs 68,000 pounds that adds up to 80,000 pounds CGW. |
| Trailer | Included in the combination’s CGW | Trailers don't get their own IRP plates. They are included in the unit's total registered weight. |
How Weight Affects Registration Fees and Multi-State Plates
Every US state and Canadian province has its own tiered fee schedule. The fees go up as the truck gets heavier and sometimes they vary by the type of vehicle configuration.
Each state has its own rules about how much you have to pay to register for the IRP which are completely different from one another. Texas, for instance, has a tiered system. A commercial vehicle that weighs between 10,001 and 18,000 pounds pays a base fee of about $110, while a vehicle that weighs 80,000 pounds pays about $840. California uses a more complicated formula that takes into account the weight and type of the vehicle, as well as other costs like the Vehicle License Fee (VLF), which is a percentage of the vehicle's current market value.
In addition to the basic weight-based fees, states also add various non-weight-related charges that contribute to the total registration cost. These may include county or district surcharges, environmental or fuel-type fees for diesel or electric vehicles and safety or inspection fees. These fees are added to the state's total annual registration cost before figuring out how to split it up.
Oversize and Overweight Vehicle Rules
The IRP takes care of registration and fee apportionment, but it doesn’t allow you to go above any weight or size limits. If your shipment is heavier or larger than what’s legally allowed on public roads, you’ll need to apply for oversize or overweight (OS/OW) permits separately.
Let’s have a look at the example:
| Scenario | Requirement | More information |
| Load Limit (≤ 80,000 lbs CGW) | Only for IRP registration | This includes most trucks that drive between states. You still have to follow the Federal Bridge Formula and the axle limits. |
| Too heavy (load that can't be split) | IRP and Overweight Permit | For cargo, machinery or heavy equipment that can't be split up. States give out permits for one trip or for a whole year. |
| Too heavy-load that can be split | Permit for a specific state | Some states, like Michigan and Idaho, let you have higher limits if you add axles and get special permits. |
| Weight declared: more than 80,000 lbs | Must be legal in all of the listed places | You can't say 100,000 lbs if one of your states only allows 80,000 lbs.You can’t declare 100,000 lbs if one of your states caps at 80,000 lbs. |
| Oversize (Width > 8.5 ft, Height > 13.5 ft, Length > 53 ft) | Oversize permit | Covers dimensional limits, not weight - IRP registration alone won’t cover this. |
Practical Compliance Checklist
Keeping your paperwork, weight declarations and permits up to date can help you avoid expensive problems on the road and failed audits.
Here’s a simple checklist to follow:
1. Weigh your truck when it's fully loaded: It makes sure that the IRP weight you say matches with the weight of your actual operations and keeps you from getting fined for not declaring.
2. Register for at least the highest legal weight on your route: It keeps your cab card valid in every state and prevents out-of-service orders.
3. Record the mileage accurately: IRP renewals use this data to split fees fairly between the states and provinces.
4. Update your registration if truck equipment or axles change: This keeps your IRP account in line with your current vehicle setup.
5. Apply for overweight/oversize permits before traveling: Applying for this type of permit helps you avoid costly fines (from $10 to $10,000+ (i.e. Texas) and roadside detention.
The heavier your truck, the more you pay and the more careful you must be about legal limits.
IRP registration keeps your operations legal across states, but it doesn’t replace overweight or oversize permits. Register correctly, track your mileage and know your route’s weight limits to stay safe and legal.
Vehicle Size Requirements Under IRP
The International Registration Plan (IRP) takes care of registering vehicles in more than one state and dividing up the fees, but it does not set or change federal or state size limits. According to 23 CFR Part 658 and the Federal-Aid Highway Act, each state has its own rules about how wide, tall and long vehicles can be. To stay in compliance, you need to know these rules.
Federal Size Standards
The Federal Highway Administration (FHWA) sets minimum requirements that all states must allow on the National Network (NN), which includes the Interstate System and key connecting highways.
These limits apply to most commercial motor vehicles (CMVs) if there are no other notes.
- Width - 102 inches (2.6 m)
Applies to the NN and “reasonable access” routes. Hawaii allows 108 inches. Mirrors, lights, and minor safety devices are excluded.
- Height - No federal limit
States set their own, generally between 13 ft 6 in (4.11 m) and 14 ft (4.27 m).
- Semitrailer Length - 48 ft minimum (some states allow 53 ft or grandfathered longer trailers)
States must allow at least a 48-ft trailer on the NN. Longer trailers depend on state grandfather rights.
- Twin Trailers - 28 ft each (8.53 m)
States must permit twin 28-ft trailers; grandfathered 28 ft 6 in units are still legal.
- Overall Combination Length - No federal limit on tractor-semitrailer combos
States cannot set an overall limit for tractor-semitrailer units on the NN but can regulate for doubles or special combinations.
- Overhang - 3 ft front / 4 ft rear
Applies to auto and boat transporters; overhang must be marked or flagged.
How Oversize and Overlength Permits Work
If a truck exceeds these limits, for example, a load wider than 102 inches or taller than 14 feet, it becomes an oversize or overlength vehicle.
In such cases, you must obtain a special permit from each state you travel through.
These permits specify approved routes, travel times, escort requirements, and marking or lighting rules. The FHWA allows states to authorize larger vehicles case-by-case, but only under permit; IRP registration alone never covers dimensional violations.
IRP and State-Specific Size Rules
IRP registration only proves your truck is legally registered across multiple states, it does not authorize operation outside each state’s size limits. Your cab card lists your declared gross weight and participating jurisdictions, but not your height or trailer length.
If your setup exceeds what’s legal in a specific state (for example, a 53-ft trailer on a secondary road limited to 48 ft), you’ll need a state oversize or route-specific permit to proceed.
In short, IRP keeps registration simple, but you must still meet every jurisdiction’s dimensional rules before hauling.
Federal vs State Size Rules
Even though federal law sets baseline size standards for trucks operating on the National Network, every state can adopt its own limits for certain dimensions, especially height, trailer length on local roads, and vehicle combinations.
The table below summarizes how federal standards compare to typical state variations and when a special permit is required for vehicles that exceed those limits.
| Category | Federal Baseline | State Variations | Permit Required Above |
| Width | 102 in (2.6 m) | Hawaii – 108 in | Overwidth permit |
| Height | None (13.5–14 ft common) | Varies by state | Overheight permit |
| Trailer Length | 48 ft minimum | 53 ft + allowed in most states | Overlength permit |
| Twin Trailers | 28 ft (each) | Grandfathered 28.5 ft allowed | Oversize combo permit |
| Combination Length | No federal limit | State-regulated on non-NN roads | Overlength permit |
| Overhang | 3 ft front / 4 ft rear | State-specific | Overhang permit |
Oversize and Overweight Vehicles
So what exactly counts as oversize or overweight?
- Overweight: Anything above 80,000 pounds total (tractor + trailer + load), unless you have a permit.
- Oversize: Anything wider than 8.5 feet, taller than 13.5–14 feet, or longer than 53 feet for a single trailer.
If you fall into either of those categories, you’ll need to apply for special oversize/overweight permits. These are handled separately from your IRP registration - you get them from each state’s Department of Transportation or permit office.
Permits and Escorts
Depending on your load and route, you might need:
- Route approval - You’ll have to follow specific roads approved for big loads.
- Pilot or escort vehicles - Cars or trucks that drive in front or behind to warn other drivers.
- Travel restrictions - Some states limit oversize moves to daylight hours or certain weekdays.
Even if you’ve got IRP registration, it doesn’t cover these special moves. Think of IRP as your license to operate between states - not a free pass for overweight or overlength hauls.
Skipping the right permits can cost you big - we’re talking heavy fines, impoundment, and sometimes even loss of your IRP privileges.
Common Mistakes Carriers Make
Let’s wrap up with a few of the most common errors drivers and carriers make when it comes to IRP, weight, and size rules:
- Registering for too low a weight to save money - then hauling more and getting fined.
- Forgetting to renew overweight permits when they expire mid-year.
- Assuming IRP covers oversize/overweight loads - it doesn’t.
- Not checking each state’s specific size rules before hitting the road.
- Failing to update mileage records - inaccurate distance reporting can trigger audits.
Keeping your registration and permits accurate may not be the most exciting part of trucking, but it’s one of the most important. When your truck’s size, weight and documents all match up, you can drive with confidence: no fines, no suspension, no worries.