The hitch's own capacity - and it is only one of several limits, all of which apply simultaneously.

Classes group hitches by rated towing weight and tongue weight, and the class also generally determines the receiver tube size.

It refers to the hitch structure alone, not to the vehicle, the ball mount, the ball or the law.

The true limit is the lowest of all of those, and fitting a higher-class hitch raises none of the others.

It is common to find a high-capacity hitch on a vehicle whose manufacturer's towing limit is far lower, and the vehicle's limit governs.

Record all the applicable figures for each vehicle rather than working from the hitch sticker, which is the one most likely to be read and the least likely to govern.

Because it sits behind the rear axle and acts as a lever, lifting the front axle and reducing steering and braking grip.

A bumper-pull trailer's download is applied well behind the rear axle.

The rear axle acts as a fulcrum, so that download transfers weight off the front axle rather than simply adding it to the rear.

A light front axle steers and brakes poorly, which is exactly the wrong outcome when the combination is at its heaviest.

Too little tongue weight is equally dangerous in a different way, because it makes the trailer prone to sway.

There is a recommended proportion of trailer weight that should sit on the tongue, and it is worth measuring rather than judging - loading the trailer differently changes it completely.

Only where a vehicle-specific hitch exists, because the hitch bolts to designed structural mounting points.

Manufacturers provide mounting points engineered to take towing loads into the vehicle's structure.

A vehicle-specific hitch uses those points, with no drilling or with drilling to a defined pattern.

Improvised hitches attached to bumpers or to convenient holes concentrate load into structure never designed for it.

Most markets have type-approval or construction-and-use requirements covering towing attachments, and an unapproved hitch can affect both roadworthiness and insurance.

Unibody and monocoque vehicles are particularly unforgiving, since there is no chassis rail to bolt to and the load path matters enormously.

Tube dimension and pin diameter, which determine capacity and which accessories will fit.

Lighter classes use a smaller square tube and a smaller retaining pin; heavier classes use a larger tube and pin.

Ball mounts, bike racks and cargo carriers are made for a specific tube size and are not interchangeable.

Reducer sleeves exist to fit a smaller accessory into a larger receiver, and they introduce additional movement and reduce the effective rating.

Pin diameter follows the tube size, so a pin from one will not correctly secure the other.

Check the receiver size on the vehicle rather than assuming from the class, particularly on aftermarket installations.

Check mounting bolt torque, inspect for corrosion and cracking around the mounts, and keep the receiver tube clear.

Mounting bolts should be checked at the first use after fitting and periodically thereafter, because they settle.

Corrosion around the mounting points is the main structural concern on older vehicles, and it happens where the hitch traps moisture against the vehicle.

Look for cracks in the hitch's own welds and in the vehicle structure around the mounts, particularly on vehicles that tow heavily.

The receiver tube collects grit and water; clearing it and keeping a plug or cover in place makes the ball mount easier to insert and remove.

Check the ball itself for wear and correct torque - a worn ball or a loose ball nut is a common and serious finding.

Above a weight threshold, yes - and the threshold, the type of braking required and the breakaway arrangements all differ by jurisdiction.

Light trailers below a defined weight are generally permitted unbraked.

Above it, trailers require a braking system, most commonly overrun braking in some markets and electric braking in others.

Electric brakes need a controller in the towing vehicle and appropriate wiring, which is a fitment consideration at the same time as the hitch.

A breakaway cable or device that applies the trailer's brakes if it detaches is generally mandatory on braked trailers.

The thresholds and the specific requirements vary considerably between jurisdictions, so check the local rule for every territory a fleet operates in.

Coupling engagement and lock, breakaway cable, lights, tyres, load security and tongue weight - as a routine rather than a glance.

Confirm the coupling is fully seated on the ball and the latch is locked, then check by attempting to lift the coupling.

Attach the breakaway cable or safety chains correctly to the designated point, not to the ball or the ball mount.

Check all lights work, including indicators and brake lights, with the trailer connected.

Check trailer tyre pressures and condition; trailer tyres frequently stand for long periods and degrade by age rather than mileage.

Confirm the load is secured and distributed so the tongue weight is within range - a load moved rearward is the usual cause of sway.