Dealers quote tow ratings. Trucks fail on payload. More often than not, the pin weight of a loaded fifth wheel uses up a truck's payload long before the trailer reaches its tow rating. This calculator checks the numbers that actually decide it — from your door sticker, not a marketing chart.
Short answer
For most pickups the limiting number is payload, not tow rating. A loaded fifth wheel
puts 20–25% of its total weight on the pin (use 22% to plan), and that weight lands in the
truck bed — counting against the payload figure on your driver's-door sticker, alongside
the hitch (≈150–250 lb), passengers, and cargo. A diesel pickup advertised to tow 25,000 lb often has only
~3,000 lb of payload, so a 12,500 lb fifth wheel (≈2,750 lb pin) can overload it while the trailer still
sits at half its tow rating. Find your real payload on the door jamb, take 22% of the trailer's loaded
(GVWR) weight as pin weight, and check that pin + hitch + people + cargo stays under it. The calculator below
does this for all four limits — payload, tow rating, GCWR, and rear axle.
Where to look: open the driver's door. The white-and-yellow Tire and Loading label says
"The combined weight of occupants and cargo should never exceed XXXX lb." That number is your real payload —
it's printed per-VIN for your exact truck, options and all. Year/make/model charts can be off by 1,000+ lb.
2 · The trailer
22%
Most loaded fifth wheels carry 20–25% of total weight on the pin. The brochure "hitch weight" is the dry pin — loaded is always higher.
3 · What rides in the truck
What no calculator can check: your actual axle weights. Stickers and percentages are the
paper check — the real check is 20 minutes and $15.25 (2026 first-weigh price) at a CAT scale (truck stops
have them), loaded for a real trip. If you're within 10% of any limit on paper, weigh before you buy.
Shareable summary
Why payload — not tow rating — is the number that decides
A modern diesel pickup might advertise a 25,000 lb fifth-wheel tow rating while its door sticker shows
3,000 lb of payload. A 12,500 lb fifth wheel puts roughly 2,750 lb on the pin at 22% — add a 200 lb hitch
and two adults, and that "half-capacity" trailer has already overloaded the truck. The tow rating never
entered the conversation.
That's not an edge case; it's the normal case. Pin weight lands directly in the bed, so fifth wheels
consume payload about twice as fast (per trailer pound) as bumper-pull trailers. It's why the forums are
full of people who bought the truck the dealer said "tows 27k" and discovered it can't properly carry the
pin of a 13k trailer. Full explanation here.
The honest rules this calculator follows: trailer weight defaults to GVWR (loaded), never
dry weight; pin weight defaults to 22% (not the brochure's dry hitch weight); your door sticker outranks
any chart, including ours.
Checking a travel trailer instead?
Bumper-pull math is different — tongue weight runs 10–15% and a weight-distribution hitch changes the
hardware. Use the travel trailer calculator.