Your tow vehicle comes with a maximum tow rating, but you also need to make sure the hitch is rated to tow the load you need.  There are a variety of hitch types, but boat trailer applications generally use hitches that mount directly to the tow vehicle’s frame.  All hitches come with both a class rating and weight rating.  There are four basic classifications, although more and more hitch manufacturers are including a fifth.

Not all hitches with the same class rating have the same weight rating, however.  Construction materials and techniques, as well as installation methods, result in different tow ratings within a given class.  The following are the basic hitch classes:

Class I: up to 2,000 pound gross trailer weight

Class II: up to 3,500 pound gross trailer weight

Class III: up to 5,000 pound gross trailer weight

Class IV: up to 12,000 pound gross trailer weight

Class V: more than 12,000 pound gross trailer weight

There are two basic types of hitches used in boat trailer towing … weight-carrying and weight-distributing.  Both are available in Class III and above.  As the name implies, weight-carrying hitches carry all the trailer tongue weight, whereas weight-distributing hitches distribute some of the tongue weight to the tow vehicle’s front and rear axles, as well as the trailer axles(s).

Weight-distributing hitches offer a considerably higher tow rating.  However, if you have a rear-wheel drive vehicle, sometimes it’s advantageous to disconnect a weight-distributing hitch when loading and retrieving a boat on steep or slippery launch ramps so that more weight is applied to the rear axle for optimum traction.

Ball mounts – the part of the hitch that you mount the hitch ball to and that slides into the receiver where it’s held in place with a removable pin – also come with different ratings depending on size and construction.  Likewise for the hitch ball, which come in different diameters (1-7/8 inch, 2 inch, 2-5/16 inch to match the trailer coupler) and with shanks of different lengths, thicknesses and hence strength.  It’s important that the tow vehicle’s receiver hitch, ball mount and hitch ball ratings are all compatible to the towed load.  If one or more of these components is improperly matched, the marriage won’t work, and you could end up with your boat and trailer divorcing itself from the tow vehicle.