To weigh your truck, pull onto a CAT Scale so your steer axle sits on the first platform, your drive axles on the second, and your trailer axles on the third, then weigh and read the ticket that shows each group plus your gross weight.
That is the short version. The longer version, the part that keeps you legal and keeps your load riding right, is worth a few minutes. Below is how a scale works, how to read the ticket, how to shift weight when a group is over, and why those three numbers matter more than most folks think.
Key Takeaways
- A standard tractor-trailer weighs on three axle groups: steer, drive tandem, and trailer tandem, plus a gross total that ties them together.
- Common federal limits are roughly 12,000 lbs steer, 34,000 lbs drive tandem, 34,000 lbs trailer tandem, and 80,000 lbs gross, but state and bridge laws can be lower.
- A first weigh costs low double digits and a same-day re-weigh at the same scale costs only a few dollars, so weighing is cheap insurance against a fine.
- Sliding your fifth wheel moves weight between the steer and drives, while sliding your trailer tandems moves weight between the drives and the trailer axles.
- A load can be legal on gross weight but still over on one group, which you fix by sliding to redistribute, not by taking freight off.
- Weight rules, scale prices, and state limits change over time, so verify current numbers with FMCSA or your state DOT before you rely on any figure.
Why Weighing Matters
You cannot eyeball 80,000 pounds. A load can sit heavy on the drives or push too much onto the steer and you would never feel it rolling down the on-ramp. Then you cross a state scale house, the light turns red, and now you are looking at a fine, a delay, and maybe a shut-down until you shift the load. Depending on the state and how far over you are, an overweight citation can run anywhere from a modest ticket to a serious penalty that climbs with every extra thousand pounds. The exact schedule is set by each state, so treat any number you hear from another driver as a rough guide, not gospel.
Weighing before you hit the highway does three things:
- Keeps you under the legal limits for each axle group and your gross.
- Protects your tires, brakes, and suspension from riding overloaded.
- Tells you if the freight is loaded balanced, which matters for how the truck handles and stops.
Think about the math for a second. A first weigh runs in the low double digits, call it a small handful of dollars for the initial pass and only a couple of dollars for the same-day re-weigh. An overweight fine, even a light one, can cost many times that, and that is before you count the load of the delay: hours parked, a late delivery, and a shipper who remembers. Weighing is one of the highest-return ten-minute habits in trucking.
The Three Axle Groups
Every legal weigh comes down to three numbers, one for each group of axles under a standard tractor-trailer. Understand what each group carries and you will understand how to fix almost any weight problem.
Steer Axle
That is the front axle under your cab. It carries the engine, the hood, and part of the cab. On most day-to-day loads the steer sits somewhere in the low-to-mid 11,000-pound range when the truck is fueled and loaded, but a heavy sleeper, a full fuel load, or a fifth wheel set too far forward can push it toward or over the 12,000-pound limit. If your fifth wheel is set too far forward, weight shifts onto the steer and you can go over.
Drive Axles
These are the powered axles under the back of the tractor, usually a tandem set. This is where a lot of the tractor weight and a chunk of the trailer weight land. On a maxed-out 80,000-pound rig the drives often carry the largest single share, frequently landing in the low-to-mid 30,000-pound range. Sliding your fifth wheel moves weight between the steer and the drives, so this is your first tool when the front and the drives are fighting each other.
Trailer Axles
The tandem set under the rear of the trailer. Sliding the trailer tandems forward or back shifts weight between the drives and the trailer axles. This is your main tool for fixing a load that is heavy in one spot. On a legal 80,000-pound load you are usually trying to land the trailer tandems somewhere in the low-to-mid 30,000-pound range, balanced against the drives.
Here are the common federal limits to keep in your head. Rules change and states can set them lower, so verify with FMCSA or your state DOT before you count on any number.
| Axle group | Common federal limit | Typical loaded range on a maxed rig |
|---|---|---|
| Steer axle | About 12,000 lbs | Roughly 11,000 to 12,000 lbs |
| Drive tandem | About 34,000 lbs | Roughly 30,000 to 34,000 lbs |
| Trailer tandem | About 34,000 lbs | Roughly 30,000 to 34,000 lbs |
| Gross vehicle weight | About 80,000 lbs | Up to 80,000 lbs |
The typical ranges above are general guidance for a fully loaded five-axle rig, not hard rules. Your real numbers depend on your tractor, fuel level, trailer, and how the freight is stacked. The only number that counts is the one on your ticket.
Note that steer axle ratings can vary with your tires and suspension. Check the tire sidewall and your door sticker, and if you are figuring tire and rolling setup you can sanity-check numbers with our Tire Size Calculator.
How to Weigh at a CAT Scale, Step by Step
- Set up before you pull on. Open the Weigh My Truck app or plan to use the intercom at the fuel desk. Have your truck number, trailer number, and company name handy so you are not fumbling while a line builds behind you.
- Line up the axles. Roll forward slowly. Put the steer on platform one, drives on platform two, trailer tandems on platform three. Painted lines on the deck show you where each platform starts and ends. If you have an extra axle, a spread, or a heavy specialized configuration, make sure each group sits fully on its own platform.
- Stop and set the brakes. Come to a full stop, set the parking brake, and stay in the cab. Do not roll during the weigh or the reading will be off.
- Call it in. Press the intercom button and give your info, or tap weigh in the app. On a busy day the intercom line can back up, which is why a lot of drivers use the app and never leave the seat.
- Get your ticket. Pick it up at the fuel desk or pull it up in the app. Check it before you leave the lot so you can re-weigh cheap if something is off.
If a group is over, slide your fifth wheel or trailer tandems to move weight, then take a re-weigh. The same-day re-weigh at the same scale costs much less than the first weigh, so use it. Many drivers plan for two weighs on any load they did not build themselves: the first to see where they stand, the second to confirm the fix.
A worked example
Say your first ticket reads like this: steer 12,300 lbs, drive 34,600 lbs, trailer 31,100 lbs, gross 78,000 lbs. Your gross is fine, well under 80,000, but your steer and drives are both over. The trailer, on the other hand, has room to spare. The picture is clear: too much weight is riding up front on the tractor.
The fix is to slide your trailer tandems forward, which pulls weight off the tractor and puts it back onto the trailer axles. On many trailers each hole you slide is worth a few hundred pounds of shift between the drives and the trailer. Move a couple of holes forward, take the cheap re-weigh, and you might land at steer 11,900, drive 34,000, trailer 32,100, gross still 78,000. All three groups legal, same total weight, just spread right. Nothing came off the trailer; the freight simply sits in a better spot now.
How to Read a Scale Ticket
A CAT Scale ticket is simple once you know the layout. You will see a line for each axle group and a gross total. It looks something like this:
| Reading | What it means | Compare against |
|---|---|---|
| Steer | Weight on the front axle | ~12,000 lbs limit |
| Drive | Weight on the tractor tandem | ~34,000 lbs limit |
| Trailer | Weight on the trailer tandem | ~34,000 lbs limit |
| Gross | All three added together | ~80,000 lbs limit |
Read it top to bottom. Compare each group to the limits above. If the gross is legal but one group is over, the load is fine in total but sitting wrong, and you fix that by sliding, not by taking freight off. If the gross itself is over, you are simply carrying too much and something has to come off before you can run legal.
Keep your tickets. They are proof you ran legal, and they help you learn how a given lane or a given shipper tends to load. Over a few months, a stack of tickets from the same customer will tell you exactly how many holes to slide before you even pull onto the scale.
Common Ways a Load Goes Wrong
- Heavy on the drives. Slide the trailer tandems forward to pull weight back onto the trailer, or slide the fifth wheel back toward the drives.
- Heavy on the steer. Slide the fifth wheel back toward the drives. Remember that a full fuel tank and a heavy sleeper both add to the steer, so a truck that was legal at a quarter tank can creep over after you top off.
- Heavy on the trailer. Slide the trailer tandems back, but watch your state bridge and kingpin rules, which limit how far back the tandems can legally sit.
Every slide moves weight between two groups, so one adjustment can help one number and hurt another. That is exactly why the cheap re-weigh exists. Move a little, weigh again, repeat until all three are legal.
Common Mistakes to Avoid
Even experienced drivers give away money and risk fines on avoidable errors. Watch for these:
- Weighing while rolling. If you creep even a foot during the weigh, the numbers can read wrong. Full stop, brake set, then weigh.
- Straddling a platform. If an axle group sits partly on two platforms, the ticket splits that weight and nothing reads right. Line up on the painted marks.
- Forgetting fuel. Fuel is heavy, and it rides mostly over the steer and drives. A truck weighed at a low tank can go over once you fill up. If you are close to the limit, weigh after fueling, not before.
- Ignoring the tandem rules. Sliding trailer tandems all the way back can put you over a state bridge-law or kingpin-distance limit even when every axle group is legal on weight. Know the rules for the states you run.
- Skipping the re-weigh. The same-day re-weigh is cheap for a reason. Guessing that a two-hole slide fixed the problem, then rolling out over the limit, is a false economy.
- Losing your tickets. A ticket is your proof you ran legal and your record of how a shipper loads. Save every one.
A Few Habits That Pay Off
Weigh loaded before a long haul, especially on freight you did not load yourself. Learn how your own tractor sits empty so you know your baseline: an empty weigh once tells you your tractor and trailer tare, and from there you can estimate available payload for any future load by subtracting tare from the legal gross. And if you are chasing fuel economy and drivetrain setup, knowing your real weight helps you dial in the rest. Our Gear Ratio Calculator is handy when you are matching your rear-end and tire setup to how the truck actually runs loaded, and the Tire Size Calculator helps when you are checking how a tire change affects your rolling setup and load ratings.
Weighing is a small step that saves real money. Ten minutes and a few dollars beats a fine, a delay, and worn-out parts every time. Line up your three groups, read your ticket, fix what needs fixing, and roll on legal.
This is general guidance for owner-operators and truck owners. Weight rules, scale prices, and state limits change. Verify current limits with FMCSA and your state DOT before you rely on any figure here.