Texas DOT Weight Regulations: Axle Limits, Permits, and Fines

Texas DOT weight limits cap any vehicle or combination on public highways at 80,000 pounds gross, with a single axle limited to 20,000 pounds and a tandem axle group limited to 34,000 pounds.¹ Those numbers come from Chapter 621 of the Texas Transportation Code and match the federal Interstate maximums under 23 U.S.C. § 127.² Running over the limit without a permit is a misdemeanor, and the fine ranges from $100 for a small overage to $10,000 for the worst violations, with repeat offenses in the same year able to double that ceiling.

Gross Weight and Axle Limits

Section 621.101 sets three ceilings that every commercial vehicle has to respect at the same time:

Single axle: 20,000 pounds, including any enforcement tolerance.
Tandem axle group: 34,000 pounds, including any enforcement tolerance.
Gross vehicle weight: 80,000 pounds, no matter how many axles or tires you run.¹

A truck can be illegal even when its gross weight is fine. If one axle is carrying 21,000 pounds while the rest of the rig runs light, that axle alone is a violation. Enforcement officers at portable and fixed scales check both totals and individual axle loads, and either type of overage triggers the same fine schedule.

One exception loosens the tandem rule. Two consecutive sets of tandem axles can each carry up to 34,000 pounds if the distance from the first axle of the front set to the last axle of the rear set is at least 36 feet.¹ Spreading the tandems apart spreads the load across more pavement, which is the same idea behind the bridge formula.

The Bridge Formula

Even a truck under all three ceilings can be overweight. Section 621.101(a)(3) requires that the weight on any group of two or more consecutive axles stay under a maximum calculated from how far those axles are spaced apart:¹

W = 500 × ((L × N / (N − 1)) + 12N + 36)

W is the maximum allowable weight for the axle group, rounded to the nearest 500 pounds. L is the distance in feet between the outermost axles in the group. N is the number of axles. Axles packed close together concentrate force on a shorter stretch of bridge deck, so they carry a lower limit than the same axles spread out.

The formula applies to every possible group of consecutive axles, not just the whole rig. The outer bridge runs from steer axle to rear trailer axle and governs gross weight. Inner bridge groups, such as the tractor axles by themselves or the trailer axles by themselves, have to satisfy the formula independently.³

For a standard five-axle combination, three checks catch almost every problem: steer through the third axle, axles two through five, and all five together. If those three pass, the smaller groupings almost always pass too.³ Short trailers and rigs with tightly spaced axles are the ones most likely to fail the formula while still reading under 80,000 pounds on the scale.

Fines for Going Over

Overweight operation is a misdemeanor, and the penalty grows with the overage. Section 621.506 uses two schedules, one for gross weight and one for axle weight.⁴

Gross Weight Fine Schedule

Under 2,500 lbs over: $100 to $500
2,500 to 5,000 lbs over: $500 to $1,000
5,001 to 10,000 lbs over: $1,000 to $2,500
10,001 to 20,000 lbs over: $2,500 to $5,000
20,001 to 40,000 lbs over: $5,000 to $7,000
More than 40,000 lbs over: $7,000 to $10,000⁴

Axle Weight Fine Schedule

When gross weight is legal but a single axle or tandem group is overloaded, the fines are lower:

Repeat and No-Permit Add-Ons

A third overweight conviction within one year of an earlier one doubles the maximum fine in that bracket, which pushes the top of the gross schedule to $20,000.⁴

Running a load that would have been legal with a permit, without getting one, adds another $500 to $1,000 on top of the weight fine. A second or later no-permit offense adds $2,500 to $5,000. The same add-on applies to any divisible load moved above 84,000 pounds, which cannot be legal without a permit.⁴

Vehicles That Get a Higher Ceiling

A few categories of vehicle can legally operate above the standard limits without a general overweight permit.

Trucks powered primarily by natural gas or electric batteries can exceed the gross limit by up to 2,000 pounds, for a total of 82,000 pounds. The allowance offsets the extra weight of alternative-fuel systems so carriers don’t lose payload for running cleaner equipment.¹ The same 2,000-pound cushion applies on the Interstate under federal law.²

Emergency vehicles designed to carry firefighting personnel and equipment get a much larger allowance under the FAST Act. States cannot enforce limits below 24,000 pounds on the steering axle, 33,500 on a single drive axle, or 62,000 on a tandem, with a gross ceiling of 86,000 pounds, and no special permit is required for Interstate travel.²

Trucks delivering groceries, farm products, or liquefied petroleum gas are exempt from reduced limits that TxDOT posts on specific state highways or farm-to-market roads. The exemption applies only to those road-specific reductions, not to the statewide ceilings in Section 621.101.⁵

Posted and County Limits That Override the Statewide Numbers

The statewide 80,000-pound limit is the ceiling, not a guarantee. TxDOT’s executive director can set lower maximums on any state highway or farm-to-market road when an engineering and traffic study shows the pavement, bridges, or culverts cannot handle the full legal load. The reduced limit takes effect once signs go up.⁵

Counties can also set their own load limits on county roads and bridges, but only with TxDOT concurrence. The county submits engineering documentation to the district engineer, and if TxDOT does not respond within 30 days, the proposed limit is deemed approved.⁶ Watch for posted signs on unfamiliar county roads, especially older bridges in rural areas, where limits can drop well below the statewide figures.

Permits for Loads Above the Limits

When a load is over the standard limits and no exemption applies, the Texas Department of Motor Vehicles issues the permit. Which permit fits depends on the load, the route, and whether the weight is divisible.

Annual Tolerance Permits

The annual tolerance permit lets a vehicle with a divisible load run up to 10 percent above the axle maximum and up to 5 percent above the gross maximum, calculated from the outer bridge distance. The permit is valid only on county roads and state-maintained highways. It does not cover the Interstate Highway System, so carriers who run mostly on interstates get no benefit from it.⁷

Qualifying requires a $15,000 Over Axle/Over Gross Weight Tolerance Permit Bond (Form 1753), or an irrevocable letter of credit, on file with TxDMV.⁷ Annual fees run from $270 for coverage in one to five counties up to $1,095 statewide across all 254 counties.⁸

Single-Trip Overweight Permits

Most one-time overweight moves use a single-trip permit tied to a specific route. Fees scale with gross weight:

At legal weight (oversize only): $60
80,001 to 120,000 lbs: $210
120,001 to 160,000 lbs: $285
160,001 to 200,000 lbs: $360
200,001 to 254,300 lbs: $470⁸

The permit has to stay in the cab for the entire movement and be shown to any inspector or officer on demand.

Superheavy Permits

Loads over 254,300 pounds gross, and loads between 200,001 and 254,300 pounds with less than 95 feet of axle spacing, need a superheavy single-trip permit and individual engineering review of pavement and bridges along the route. Applications should go in three to four weeks before the planned move to allow time for review. TxDMV also checks the carrier’s USDOT number against FMCSA records for out-of-service orders before issuing the permit.⁹

How to Apply

All overweight permit applications go through the Texas Permitting and Routing Optimization System (TxPROS), which lets carriers apply online and self-issue many permits with built-in GIS route checking against current restrictions.¹⁰ Have the vehicle’s year, make, and VIN ready, along with combined length, width, and height, the requested gross and axle weights, and the exact origin, destination, and route inside Texas. TxDMV uses that route to verify every bridge, overpass, and road segment can carry the load, so vague routes or bad measurements get applications kicked back.

Why Permits Don’t Solve the Interstate Problem

Texas weight law tracks 23 U.S.C. § 127, and that alignment is not accidental. Federal law requires states to allow up to 80,000 pounds (with 20,000 on a single axle and 34,000 on a tandem) on the Interstate System, and the federal bridge formula is the same one Texas uses.²

Where the systems part ways is above 80,000 pounds. Texas overweight permits can authorize excess weight on state highways, but they generally cannot authorize it on the Interstate because federal law controls those limits. Tolerance permits, for example, explicitly exclude the Interstate System.⁷ If you’re moving overweight, plan the route on state highways where the permit is valid.

1
State of Texas. Texas Transportation Code 621.101 – Maximum Weight of Vehicle or Combination
2
Office of the Law Revision Counsel. 23 USC 127 – Vehicle Weight Limitations
3
Federal Highway Administration. Bridge Formula Weights
4
State of Texas. Texas Transportation Code 621.506 – Offense of Operating or Loading Overweight Vehicle; Penalty; Defense
5
State of Texas. Texas Transportation Code 621.102 – Authority to Set Maximum Weights
6
Cornell Law Institute. 43 Texas Administrative Code 25.2 – Load Limits on County Roads and Bridges
7
Texas Department of Motor Vehicles. Annual Over Axle/Over Gross Weight Tolerance Permits
8
Texas Department of Motor Vehicles. Oversize/Overweight Permit Fees and Credit Card Payments
9
Texas Department of Motor Vehicles. Superheavy Single-Trip Permits
10
Texas Department of Motor Vehicles. TxPROS Information and Tutorials