Methodology: how we source and check every number

Where the numbers come from

Every vehicle figure on this site is traceable to a published source, and the source is shown on the page next to the number. We use, in order of authority:

• Manufacturer towing guides (primary). Ford, GM, Ram, Toyota and others publish annual towing guides that break capacity down by engine, transmission, axle ratio, cab, and tow package — the config-level detail that single-number lookups flatten. This is our main source and our point of difference.
• NHTSA vPIC (catalog skeleton). The government vehicle database gives us the authoritative list of makes, models, years, and body classes to build page structure around. It does not publish towing capacity, so we never use it for the number itself.
• Historical tow guides (Trailer Life / Good Sam archives). For older model years we cross-reference the annual whole-market tow guides.
• Independent spec databases (cross-check only). We compare against third-party trim databases to catch transcription errors — never as the sole source of a number.

Towing figures are facts, not creative works, and facts are not copyrightable (Feist v. Rural). We compile them, cite them, and add the interactive math around them.

How we check them (the QA layer)

Before any record can appear on the site it passes automated checks:

• Cross-source agreement. A figure that disagrees across sources is flagged for a human to resolve, and we publish the lower value until it's resolved.
• Plausibility ranges. Every record is range-tested — tow rating, payload, curb weight, GCWR and axle ratio must fall inside physically plausible bands, and cross-fields must agree (for example, GCWR has to cover curb weight plus the tow rating). Records that fail are held back, not shown.
• Conservative rounding. Any limit we derive (like the payload-bound trailer weight) is rounded down to the nearest 10 lb. We would rather understate capacity than overstate it.

Confidence grading

Each number carries a grade so you know how firm it is:

• J2807 — tested to the SAE J2807 standard (industry-standard since 2013–2015). What that means →
• Manufacturer — an OEM-published rating from before or outside J2807.
• Estimated — interpolated where a specific config wasn't published; always labeled, never presented as a hard figure.

Why we show the limiting factor

A truck's advertised tow rating is only one of four limits. The real ceiling is the smallest of the tow rating, the GCWR headroom, the payload available for tongue weight, and the hitch class. On half-ton trucks the binding limit is usually payload, not the tow rating — so we compute all four and name the one that stops you first.

How the calculator does the math

Where we have a choice, we take the one that protects you rather than the one that flatters the truck:

• Conservative tongue weight (default). A trailer's tongue weight is a share of its loaded weight — roughly 10–15% for a bumper-pull, 15–25% for a fifth-wheel. By default the calculator plans for the heavy end (15% / 25%), because it's the tongue weight, riding on the truck, that eats your payload first. You can switch it off, but a lightly-estimated tongue is how people end up over their payload without knowing it. More on tongue weight →
• Real factory receiver rating over the generic class. When a towing guide publishes the actual rating of the factory receiver, we use that number instead of the nominal hitch-class table — a factory 2" receiver is often rated well above its class.
• Rear axle (GAWR) is a caution, not a fake number. On most trucks the thing you overload first is the rear axle, because tongue weight lands right over it. We flag that and tell you to weigh the rear axle — we do not invent a precise rear-axle trailer limit, because an honest one needs your wheelbase and hitch geometry, which we don't have. The right answer is a CAT scale, not false precision.
• Payload we can't verify isn't guessed. If we don't have a payload figure for your exact configuration, the calculator says so and asks for your door-jamb number — it will not dress the brochure tow rating up as your real limit.

Corrections

If you find a number that doesn't match your vehicle's door-jamb sticker or towing guide, tell us on the contact page with the source and we'll fix it. Ratings change with model-year revisions; we date every page and re-check on a schedule.

See also the full list of data sources and our safety disclaimer.