About TowingCalc

TowingCalc publishes towing calculators, reference charts and buying guidance for RV and consumer trailer towing. Tongue weight, pin weight, cargo carrying capacity, payload, hitch classes, ball and coupler matching, weight distribution, sway, brake controllers, trailer tires, grades and truck campers.

The three kinds of number, and why we label them

Towing advice mixes three kinds of figure that look identical on a page and are not remotely equivalent. Getting them confused is how somebody ends up towing a trailer their truck cannot carry, so we mark every table and every headline figure with which one it is:

• A published standard. A traceable figure: SAE J684 ball and coupler dimensions, tire load index tables, load range to maximum cold inflation, the definitions of GVWR, GCWR, GAWR and cargo carrying capacity, the SAE J2807 tow rating test methodology. These do not change because somebody on a forum disagrees.
• A convention. Something the towing community broadly agrees on that no standards body publishes: the 10 to 15 percent tongue weight band, the 15 to 25 percent pin weight band, the "stay under 80 percent" comfort rule, a brake controller gain starting point. Useful, widely taught, and not a specification.
• A figure from your own vehicle. The payload sticker in your door jamb, the certification label on your trailer A-frame, the tow rating in your owner manual for your exact configuration. Nothing on this site can supply one of these, so every calculator takes them as an input instead of guessing.

What we will not publish, and why

Per-vehicle tow rating tables. This would be the highest traffic page we could build and we are not building it. A tow rating belongs to one exact combination of engine, axle ratio, cab, bed and drivetrain, not to a model name, and two trucks wearing the same badge routinely differ by thousands of pounds. A table indexed by model name is wrong by construction for most of its rows, and wrong in the direction that gets somebody hurt. We build those pages around the arithmetic instead, which teaches something a lookup table cannot.

A per-state trailer brake table. There is no single federal weight at which a light trailer must have brakes. It is state law, it genuinely varies, commonly somewhere between 1,500 and 5,000 lb, and some states set it by a ratio to the tow vehicle instead. We could not source all fifty reliably, and a wrong row would be worse than no row, so we say it varies and tell you to check your own state and your trailer certification label.

Any sentence that names a particular truck or SUV and then states a trailer weight it is able to pull. We give you the arithmetic and the margins. You check your own door jamb. That is not us being unhelpful, it is the only honest way to answer the question. (This paragraph deliberately describes that forbidden sentence rather than spelling one out. Written literally, as an example, it would be indistinguishable from the real thing to any automated check looking for exactly that pattern, and a statement of a rule should never be able to fail the check for that rule.)

Commercial trucking. Cost per mile, IFTA fuel tax, hours of service, per diem and CDL topics are owner-operator calculations rather than RV ones. They live on our sister site, TruckingCalc, and we link there rather than duplicating them.

How we research products

We do not test towing hardware in person and we never claim to. Recommendations are researched from manufacturer specification sheets and towing guides, published standards, and the recurring themes in verified owner reviews. Where a manufacturer does not publish a figure, we leave the cell blank rather than estimating it: on a site about load ratings, a plausible looking guess in a table is more dangerous than an honest gap.

Our catalog currently holds 174 products, every one of which had its ASIN resolved live and its returned title read against the product the page claims it is. Prices, images and links come from that live data rather than being typed, which is why they do not drift.

We also reject a great deal. Searching almost any towing term returns a wall of near-identical listings from sellers with no service path, no published test basis and no warranty worth the word. For a phone case that is a matter of taste. For a weight distribution hitch, a brake controller, a trailer tire or a set of safety chains, it is a part whose failure puts a loose trailer on a public road. Trailer safety chains were the clearest case: every result on that search was an untraceable seller, so we catalogue none at all and link a scoped search instead. The full reasoning is recorded in the source file that generates the catalog.

What is on the site

• 249 computed pages generated from the same formulas the calculators use, so the figures cannot disagree.
• 40 hardware spec sheets carrying only manufacturer-published ratings.
• Calculators that show their formula on the page and report margins rather than verdicts.
• Reference charts written to be quoted, with every table labelled by basis.

Corrections

If a figure here is wrong, we want to know, and we would rather hear it bluntly than not at all. Get in touch through the contact page. We cannot tell you whether your specific vehicle can tow your specific trailer, and we will not try, but we will happily walk through the arithmetic with you.