The number on platform 3 of your CAT ticket is not what your trailer weighs. Part of that trailer rides on your truck through the hitch, so its load lands on platforms 1 and 2, and one pass over the scale can't tell you how much. Three tickets can. Budget about half an hour (most of it unhitching) and a few dollars in reweigh fees. The math afterward takes thirty seconds.
Our take: the pass that's easiest to skip, the one with the weight distribution bars released, is the only one that gives you real tongue weight and front axle restoration. Skip it and you're guessing at the number that, as RV LIFE warns, can quietly use up your truck's payload while the trailer itself looks fine.
Why does a proper trailer weigh take three passes, and what does each one measure?
CAT Scale's own instructions say the whole rig must be on the scale, with the truck's steer axle (front wheels) on platform 1 and the drive axle (rear wheels) on platform 2. The trailer normally shows up on platform 3. That layout is the same for a bumper-pull travel trailer, a fifth wheel and a boat trailer.
Each pass answers a different question:
- Pass 1, hitched, bars engaged. This is how you actually drive. It gives your gross combined weight (GCW) and the real axle loads you check against the ratings.
- Pass 2, hitched, bars released. The full tongue load sits on the truck, with no leverage spreading it. Compared with pass 3, it gives true tongue weight. Compared with passes 1 and 3, it gives front axle restoration.
- Pass 3, truck alone. Same people, same gear, platform 3 empty. This is the baseline. Without it, you can't work out either number.
Two exceptions. If you're weighing a spread-axle trailer, CAT says you'll need to move the truck during the weigh, so expect two positions. If you drive a tag axle motorhome, CAT asks you to call 1-877-228-7225, ext 6 before weighing to get the correct weight.
The three CAT passes and what each one gives you
- Pass 1: bars engagedThe rig as you drive it. Gives GCW and the axle loads for the ratings check.
- Pass 2: bars releasedFull tongue load on the truck. Needed for tongue weight and front axle restoration.
- Pass 3: truck aloneSame people and gear, platform 3 empty. The baseline for both calculations.
- Do the mathTongue weight, trailer weight, tongue %, restoration % and the margin under each rating.
How do you do the weigh at the truck stop, step by step, and what does it cost?
Load the rig the way you travel. RV LIFE's rule: weigh fully loaded, with passengers, food, clothing, water, fuel, supplies and anything being towed, and use the result for your tire inflation tables. Then:
- First weigh. Pull on slowly. Stop with the steer axle on platform 1, the drive axle on platform 2 and the trailer axles on platform 3, with no tire sitting on a seam. Press the intercom button and say: "First weigh, private vehicle with a trailer. I'll be reweighing." Give a name when asked.
- Pay and keep the number. Pay at the fuel desk and write down the weigh number printed on the ticket.
- Second pass. Park where the truck stop allows, release the spring bars, loop back around and say "Reweigh," followed by that number.
- Third pass. Unhitch in a spot the staff okays, then bring the truck across alone. "Reweigh" again, same number.
- Leave set up. Rehitch, then put the bars back on and tighten them before you pull out.
These are estimates. Prices vary by location, and the desk price is the one that counts.
CAT's Weigh My Truck app saves you the walk inside. You pay in the app and the weights arrive on your phone. Run all three passes from the same account so the reweighs attach to the first weigh.
The other classic mistakes: an axle hanging past the platform edge, weighing the truck alone with the bed emptied, and driving off with the bars still loose. Get those right and the tickets tell you what the trailer really weighs.
How do you read a CAT Scale ticket: steer, drive, trailer and gross?
A CAT ticket stacks four weights:
- Steer axle: platform 1.
- Drive axle: platform 2.
- Trailer axle: platform 3.
- Gross: the sum of the three.
Near the top you'll find the weigh number you quote for reweighs, plus the date and time stamp. On the truck-alone pass, the trailer line reads zero and the gross is your loaded truck weight.
What the ticket can't show: according to RV LIFE, CAT gives axle weights and gross weight but not individual wheel-position weights. A truck loaded heavy on the left looks normal here. For side-to-side balance, RV LIFE points to wheel-position weighing at an Escapees SmartWeigh event or an RV Safety and Education Foundation (RVSEF) rally.
Before you leave the lot, copy eight numbers onto one ticket: all three platform readings from pass 1, all three from pass 2, and the first two platforms from pass 3. Every calculation below runs on those eight.
How do you turn three tickets into real tongue weight and front axle restoration?
Two formulas cover it:
- Tongue weight = (pass 2 steer + pass 2 drive) minus (pass 3 steer + pass 3 drive)
- Trailer weight = tongue weight + pass 2 trailer axle
Say you tow a roughly 7,000 lb travel trailer with a half-ton crew cab. With the example tickets, the truck carries 7,450 lb with the bars released and 6,600 lb alone. Tongue weight is 850 lb. Add the 6,150 lb on platform 3 and the trailer weighs 7,000 lb, so the tongue carries 12.1% of it.
A bumper pull below 10 percent is the classic setup for sway.
In the example, the tongue lifted 260 lb off the steer axle and the bars put 150 lb back: 58%.
Some truck makers print their own target in the owner's manual, and that figure wins. If you can't reach it, a hitch installer or dealer can adjust the bar tension or head tilt.
One sanity check: the gross should match between passes 1 and 2 (13,600 lb both times in the example), because releasing the bars moves weight around without adding any. If those two figures are more than a few dozen pounds apart, something changed between passes. Once they agree, move on to the ratings.
Real tongue weight from your CAT tickets
Example: Pass 2 (bars released) steer axle: 3,240 lb, Pass 2 (bars released) drive axle: 4,210 lb, Pass 3 (truck alone) steer axle: 3,500 lb, Pass 3 (truck alone) drive axle: 3,100 lb. Result: 850 lb.
Takes the truck's steer plus drive with the bars released and subtracts the truck's steer plus drive when weighed alone. Keep the same load and the same fuel in both passes. The defaults are the page's illustrative half-ton example.
Tongue weight as a percent of trailer weight
Example: Pass 2 (bars released) steer axle: 3,240 lb, Pass 2 (bars released) drive axle: 4,210 lb, Pass 2 (bars released) trailer axles: 6,150 lb, Pass 3 (truck alone) steer axle: 3,500 lb, Pass 3 (truck alone) drive axle: 3,100 lb. Result: 12.1 %.
Tongue weight divided by total trailer weight, where trailer weight is tongue weight plus the pass 2 trailer axle reading. Compare it with the ranges in the section: about 10 to 15% for a conventional trailer and 15 to 25% for a fifth wheel or gooseneck.
Front axle load restoration with the WDH engaged
Example: Pass 1 (bars engaged) steer axle: 3,390 lb, Pass 2 (bars released) steer axle: 3,240 lb, Pass 3 (truck alone) steer axle: 3,500 lb. Result: 58 %.
Weight the hitch puts back on the steer axle (pass 1 minus pass 2) divided by the weight the tongue took off it (pass 3 minus pass 2). Check the result against the figure in your truck's owner's manual. Above 100% means the front is heavier than with no trailer.
How do you check the numbers against GVWR, GAWR, GCWR and the hitch rating?
Each rating lives in a different place:
- GVWR and front and rear GAWR: the sticker on the driver's door jamb.
- GCWR: the owner's manual or the maker's towing guide for your exact configuration.
- Hitch and receiver ratings: stamped on the parts, and the ball carries its own. The lowest one is your limit.
Use pass 1 for GVW (steer plus drive), both axle ratings and GCW. Use the tongue weight from passes 2 and 3 against the hitch and receiver ratings. Tires get checked separately against the maximum load on the sidewall. RV LIFE's list covers all of it: GVWR, GAWR, GCWR, tire load ratings, payload, hitch rating and receiver rating, and it says to reduce or redistribute weight if you're close to or over any of them.
In the example, both axles pass. GCW passes with 1,400 lb to spare. The 850 lb tongue clears a 1,000 lb hitch. And the truck still comes in 70 lb over its 7,350 lb GVWR. That's the trap RV LIFE describes, where the hitch weight eats the truck's payload. Passing on the total isn't enough either: RV LIFE notes a vehicle can sit under GVWR and still be heavy on one axle.
Which fix fits your rig is a question for your truck maker's towing guide or a hitch professional.
The half-ton example at a glance (illustrative)
- 850 lbReal tongue weight from passes 2 and 3
- 12.1%Tongue weight share of a 7,000 lb trailer
- 58%Front axle load restored by the bars
- 70 lb overTruck GVW against a 7,350 lb GVWR
Tightest margin against your ratings (negative means over)
Example: Pass 1 (bars engaged) steer axle: 3,390 lb, Pass 1 (bars engaged) drive axle: 4,030 lb, Pass 1 (bars engaged) trailer axles: 6,180 lb, Pass 2 (bars released) steer axle: 3,240 lb, Pass 2 (bars released) drive axle: 4,210 lb, Pass 3 (truck alone) steer axle: 3,500 lb, Pass 3 (truck alone) drive axle: 3,100 lb, Truck GVWR (door-jamb sticker): 7,350 lb, Front GAWR (door-jamb sticker): 3,900 lb, Rear GAWR (door-jamb sticker): 4,150 lb, GCWR (owner's manual or towing guide): 15,000 lb, Hitch or receiver tongue weight rating, whichever is lower: 1,000 lb. Result: -70 lb.
Do RVs and pickups have to stop at state weigh stations, and what does the CAT guarantee cover?
Each state writes its own weigh station rules. Some states post signs for "all trucks" or set a weight that a pickup towing a heavy trailer can cross, and a rig used for business can count as commercial. Check the DOT or state police site for each state on your route.
CAT backs its numbers. If a state fines you for being overweight after a CAT scale showed you legal, CAT says it will check the scale right away. If the scale was wrong, it reimburses the fine. If it was right, a CAT representative goes to court with you as a witness.
Weigh again whenever the setup changes: a new trailer, a new hitch or bar adjustment, a big change in what you carry, or the start of a long season.
This is general information, not personal advice. Before you decide, check with a qualified professional.
Frequently asked questions
Do I need all three passes if I don't use a weight distribution hitch?
No. Without spring bars there's nothing to release, so two passes do it: the hitched rig and the truck alone. Tongue weight is the truck's steer plus drive hitched, minus steer plus drive alone.
Can I weigh just the trailer on its own?
There's no need, and a truck stop won't want an unhitched trailer left on the scale. Add the tongue weight from your tickets to the platform 3 reading and you have the full trailer weight.
Should I weigh with the fresh water tank full?
Weigh it the way you travel. If you sometimes leave with a full tank, a pass with it full shows your worst case.
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