Free tool for dump truck buyers
Compare two dump trucks, such as a tri-axle and a quad. See the legal payload of each on the Interstate and on your state’s roads, how many loads a day the haul allows, the rate per ton you need, and how fast one more axle pays for itself.
1 · Your two trucks
Starting values are a typical South Carolina tri-axle and quad. Each added lift axle usually adds about 1,300 to 1,900 lb of empty weight.
2 · Your state and route
Dump trucks are exempt from axle spacing off the Interstate. Gross by axle count, 10% scale tolerance included (SC Code 56-5-4140).
3 · The haul
Take the one-way drive time from a map app and add a little, since loaded trucks run slower than cars. 2.25 minutes a mile is a common starting point.
4 · What the bigger truck costs
Adding one steerable lift axle typically runs $18,000 to $25,000 with the air controls, frame extension and longer body. Upkeep starts at one set of lift-axle tires a year ($550 to $850 a tire); add brakes and air springs if you track them.
Legal payload
| Interstate | SC roads | |
|---|---|---|
| A · Tri-axle | 17.55 t 61,600 lb gross | 21.68 t 69,850 lb gross |
| B · Quad | 20.38 t 68,750 lb gross | 21.75 t 71,500 lb gross |
| B gains | +2.83 t | +0.08 t |
Payload is legal gross minus empty weight, in tons. Interstate: Truck A is limited by the Bridge Formula plus SC’s 10% tolerance, Truck B by the Bridge Formula plus SC’s 10% tolerance.
The money, on South Carolina roads
On South Carolina roads, Truck B carries about the same as Truck A, so the extra axle doesn’t pay on ton-rate work here.
Loads per day are rounded down, since a partial load doesn’t pay. On hourly work (most dirt and asphalt), extra payload only pays if the job pays more for a bigger truck.
General information, not legal advice. Weight laws change, and local roads, bridges and permits can set lower limits. Confirm with your state DOT before you spec a truck. Nothing you enter leaves your device.
How it works
The calculator works out the legal payload of two trucks on the Interstate and on your state’s roads, then prices the difference. In some states a quad carries no more than a tri-axle off the Interstate; in others every added axle pays.
Why the answer changes so much from state to state, with a 14-state table and a worked South Carolina example: How many axles should your dump truck have?
FAQ
General information, not legal advice. Confirm weight limits with your state DOT before you spec or load a truck.
It uses the federal limits for straight trucks: 20,000 lb on a single axle, 34,000 lb on a tandem, 80,000 lb gross and the Bridge Formula across all axles, with the outer bridge rounded to the nearest foot. South Carolina keeps older, grandfathered Interstate limits that add its 10% enforcement tolerance, so for South Carolina it adds 10% within the state’s caps. Many other states keep grandfathered Interstate limits too; for them it uses the federal limits, so your state may allow more. It shows which limit controls each truck.
Alabama, Florida, Mississippi, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Texas and Virginia, using rules we read in each state’s law in October 2026. Optional permits and material allowances are explained but not added. For any other state, choose “Another state” and enter the gross your state allows. Our dump truck axle article covers 14 states.
A partial load doesn’t get paid. If the day fits 8.7 cycles, the truck hauls 8 loads, so the calculator counts whole loads only.
No. It checks the whole truck. The rear group (pushers plus tandem), the steer axle rating and tire ratings must also pass. On typical dump truck spacing the overall limit controls, but tight pusher spacing or a light front axle can lower what you can haul.
Your entries are saved only in this browser on this device, so they are there next time. Nothing is sent to VTA or anyone else.
Federal limits: 23 CFR 658.17. State rules: SC Code 56-5-4140, 75 Pa.C.S. 4941, Fla. Stat. 316.535(6), Ala. Code 32-9-20, N.C. G.S. 20-118, Miss. Code 63-5-33, Va. Code 46.2-1126, Tex. Transp. Code 621.101, Ohio Rev. Code 5577.04, N.Y. VTL 385. Checked October 2026.
Tell us what the scales allow where you haul. Crew members are helping VTA build a dump truck weight guide for all 50 states.