Meet TongueCheck — Decode your CAT scale slip

Utilities

TongueCheck

Decode your CAT scale slip

What TongueCheck does

Three numbers on a CAT scale slip stand between you and a safe tow — if you know what to do with them. Most people don't. They pay for the weigh, get a receipt with steer, drive, and trailer axle weights, and then sit in the truck stop parking lot trying to remember which pass to subtract from which and what any of it means for the payload sticker in the door jamb. The forums are full of the same question: help me decipher my scale ticket. TongueCheck answers it on the spot, offline, in the time it takes to type in six numbers.

Set up your rig once. Enter the tow vehicle's ratings from the door sticker and owner's manual — GVWR, GCWR, front and rear axle ratings, payload, receiver limits — and your trailer's ratings alongside. Then at the scale, log each weigh pass: truck alone, hitched with the bars off, hitched with the bars on. TongueCheck instantly derives everything the slip never prints: actual tongue weight, tongue percentage, trailer weight, gross combined weight, remaining payload, and exactly how much front-axle load your weight-distribution hitch restored. Fifth-wheel owners get the same treatment with pin weight and pin percentage.

Every rating becomes a plain red, yellow, or green margin card — you see at a glance that your rear axle has 380 pounds of headroom and your tongue sits at 12.4 percent, right in the safe band. Tongue weight outside 10 to 15 percent is the classic setup behind trailer sway, and TongueCheck makes that one number impossible to miss.

Because loadouts change, every weigh is saved. Add firewood, a generator, a second bike rack — the cargo ledger tracks what each item weighs and where it rides, so you see remaining payload shrink before the scale confirms it. Compare seasons, and export a clean weigh report as your record of a dialed-in rig.

TongueCheck runs entirely on your device: no account, no signal needed at the scale, no data leaving your phone. Your ratings, your numbers, your margins — finally legible.

• Rig garage for tow vehicle and trailer ratings, entered once • CAT scale multi-pass decoder: tongue weight, tongue percent, trailer weight, GCW • Red, yellow, green margin cards for GVWR, GCWR, axles, payload, and receiver • Weight-distribution hitch before and after comparison with front-axle restoration • Fifth-wheel pin weight and pin percent mode • Cargo ledger that tracks gear weight against remaining payload • Weigh history and shareable PDF weigh report • Fully offline, no account needed

A look inside

Tap any screenshot to open the full-resolution version.

What's inside

• Rig Garage — Store each tow vehicle's GVWR, GCWR, front/rear axle ratings, payload sticker, and receiver limits, and each trailer's GVWR, axle rating, and type (travel trailer or fifth wheel) — entered once from the door sticker and never re-derived.
• Slip Decoder — Log the steer, drive, and trailer axle weights from each CAT scale pass (truck only, hitched bars off, hitched bars on) and instantly get tongue or pin weight, tongue percent, trailer weight, GCW, and remaining payload.
• Margin Cards — Every rating in the rig garage becomes a red, yellow, or green card showing pounds of headroom against GVWR, GCWR, each axle, payload, and receiver tongue limit — the whole safety picture at a glance.
• WDH Comparison — Side-by-side bars for front, rear, and trailer axle weights with the weight-distribution hitch tensioned versus removed, plus the front-axle load restoration percent that tells you whether the hitch is dialed in.
• Cargo Ledger — Track each item of gear (weight, where it rides: cab, bed, or trailer) and watch remaining payload and projected tongue weight update before you ever hit the scale.
• Weigh History & Report — Every weigh session is saved per rig so you can compare loadouts season to season, and any session exports as a clean one-page PDF weigh report.

Why we built it

Deriving tongue weight, WDH effectiveness, and GVWR/GCWR/axle/payload margins from a multi-pass CAT scale receipt is confusing enough that owners post 'help me decipher my scale slip' threads on every RV forum — and getting it 10% wrong means trailer sway or a bent axle.

What makes it different

CAT's own WeighMyTruck app locates scales and pays for the weigh but does zero interpretation — no tongue weight, no margins, no history. The lone free App Store competitor, GVWR (id1524525204), is stale since 2023 with 3.0 stars on 2 ratings, a fixed kingpin percentage, and reviews saying it breaks on real scale read…

Who it's for

Anyone who values a small, sharp, single-purpose tool that does one job well and stays out of the way.

In one line: Decode your CAT scale slip

Try it

See the Decode your CAT scale slip for the full feature list, the info table, and support links.

Use TongueCheck, found a bug, or have a feature request? Comments are open below — anonymous is fine.