Tri axle dump truck vs quad and quint axle: legal tons, yards and cost
Steve Woods · Truck Dispatcher, TruckSprint
Steve Woods is a truck dispatcher with 9 years of experience in trucking. He reviews every guide we publish. How we research and update guides.
Updated October 2026
Quick answer
A tri axle dump truck has four axles, including one lift axle. On the Interstate, the Bridge Formula lets it gross 56,500 lb with 22 ft between first and last axles, about 13 tons of payload. A quad (5 axles) at 26 ft grosses 64,500 lb and a quint (6 axles) at 28 ft 71,000 lb.
Source: 23 CFR 658.17 (Bridge Formula); empty weights are EXAMPLES · checked 2026-10
Most pages say a tri-axle carries 18 to 25 tons without naming the road. On the Interstate, the federal number is lower, and on many state roads it's higher. I'm Steve Woods, a truck dispatcher at TruckSprint with 9 years in trucking. Here's each setup by the law, by the yard and by the dollar.
What tri, quad and quint mean
Count every axle on the ground, steer included:
| Setup | Axles | Usual layout |
|---|---|---|
| Tandem | 3 | Steer + 2 drives |
| Tri-axle | 4 | Steer + 2 drives + 1 lift axle |
| Quad | 5 | Steer + 2 drives + 2 lift axles |
| Quint | 6 | Steer + 2 drives + 3 lift axles, or a lift plus a trailing booster |
Lift axles count only when they're down and carrying weight. A tri-axle with its pusher up weighs in as a tandem. For the full family, from single axles to off-road haulers, see types of dump trucks; trailing-axle setups are in the super 10 dump truck guide.
Tri axle dump truck capacity: legal gross by axle span
The federal Bridge Formula in 23 CFR 658.17 sets gross weight on the Interstate from the number of axles and the distance from first to last. Longer spacing allows more.
| First to last axle | Tri-axle (4) | Quad (5) | Quint (6) |
|---|---|---|---|
| 20 ft | 55,500 lb | 60,500 lb* | 66,000 lb* |
| 22 ft | 56,500 lb | 62,000 lb | 67,000 lb* |
| 24 ft | 58,000 lb | 63,000 lb | 68,500 lb |
| 26 ft | 59,500 lb | 64,500 lb | 69,500 lb |
| 28 ft | 60,500 lb | 65,500 lb | 71,000 lb |
Source: 23 CFR 658.17, Bridge Formula W = 500(LN/(N-1) + 12N + 36), rounded to the nearest 500 lb · checked 2026-10
*Short spans marked with an asterisk are rare for that many axles; shown for the math only. Each axle group inside the truck has to pass too, and the steer axle is limited by its tire and axle ratings. Run your exact spacing in the bridge formula calculator.
How many tons and yards each one hauls
Subtract the empty weight from the legal gross and you have payload. Then divide by the material's weight per yard.
Tri vs quad vs quint. EXAMPLE spans and empty weights, edit them
Gross from the federal Bridge Formula (23 CFR 658.17) over all axles, capped at 80,000 lb; each axle group must also pass, so check yours in the bridge formula calculator. Interstate only: states set their own limits on state roads. Caltrans rates exclude the operator. Used prices: our TruckPaper snapshot, October 27, 2026.
| EXAMPLE, Interstate | Tri at 22 ft | Quad at 26 ft | Quint at 28 ft |
|---|---|---|---|
| Legal gross | 56,500 lb | 64,500 lb | 71,000 lb |
| EXAMPLE empty weight | 30,000 lb | 33,000 lb | 36,000 lb |
| Legal payload | 13.25 tons | 15.75 tons | 17.5 tons |
| Gravel at 1.42 t/yd³ | 9.3 yd³ | 11.1 yd³ | 12.3 yd³ |
| Base course at 1.25 t/yd³ | 10.6 yd³ | 12.6 yd³ | 14.0 yd³ |
| Fill dirt at 0.8 t/yd³ | 16.6 yd³ | 19.7 yd³ | 21.9 yd³ |
Source: New Mexico EMNRD Mining and Minerals Division, conversion factors (cubic yards to short tons, adapted from a BLM handbook) · checked 2026-10
That's why the yards printed on a body rarely match a ticket: heavy material reaches the weight limit long before the body is full. Your empty weight is the number to get right; weigh the truck on a certified scale with fuel and the driver. Dump truck capacity walks through struck and heaped yards.
On state roads
Off the Interstate, each state sets its own axle and gross limits, and many give dump trucks higher limits or grandfathered tables. That's where the 18-to-25-ton tri-axle figures come from. They're legal only where your state says so. Check your state's size and weight office, or start with the truck weight limit checker.
What each one earns per hour
Public rate schedules price equipment by axles. Caltrans's schedule (effective September 1, 2026) pays these per hour for on-highway dump trucks on its contracts, operator not included:
| Caltrans TRUON | Per hour |
|---|---|
| 4 axles (tri) | $111.72 |
| 5 axles (quad) | $125.52 |
Source: Caltrans, Labor Surcharge and Equipment Rental Rates (effective Sept 1, 2026 - Mar 31, 2027), TRUON Trucks, Dump, On-highway · checked 2026-10
Caltrans lists no 6-axle class. On per-ton work, the extra tons are the pay: an EXAMPLE quint carries 4.25 more legal tons per Interstate trip than the EXAMPLE tri. Both schedules are in dump truck hauling rates.
What each one costs
From our October 27, 2026 snapshot of TruckPaper dump truck listings (asking prices, median):
| Setup | New | Used |
|---|---|---|
| Tri-axle | $245,900 | $119,900 |
| Quad | $267,900 | $149,500 |
| Quint and up | $278,613 | $139,750 |
Source: TruckPaper.com, Dump Trucks category, all new and used listings (our count and quartiles) · checked 2026-10
New, the three sit within about $33,000. Used, a quad asked more than a quint at the median, because the used quint pool skews older. Ranges, model years and the cost to own are in how much a dump truck costs.
Which one to buy
- Tri-axle if your work is mixed: site work, aggregate, asphalt, tight jobs. It's the most listed setup and the easiest to find work and parts for.
- Quad if your state's road limits reward the fifth axle and your work is mostly heavy aggregate on per-ton pay.
- Quint only if your state's tables let you use the weight, and you have steady per-ton work to pay for the extra axles, tires and lift-axle upkeep.
Before you buy any of them, price the job on Interstate weight and on your state's weight, and buy for the one you'll actually drive.
TruckSprint no longer dispatches dump trucks. Running a 26 ft box truck too? That one we can keep loaded.
Sources
- 23 CFR 658.17 (Bridge Formula), eCFR; FHWA Bridge Formula Weights
- New Mexico EMNRD material conversion factors
- Caltrans Labor Surcharge and Equipment Rental Rates, effective September 1, 2026
- Our TruckPaper Dump Trucks listing snapshot, October 27, 2026
- California Vehicle Code 35400 (vehicle length)