Treilerit

Treilerit, or trailers, are non-self-propelled vehicles designed to be towed by a motor vehicle. They are used to transport goods, equipment, or, in some designs, living space. The Finnish term treileri is common for road-towed platforms, with treilerit being the plural. While travel trailers (caravans) provide housing, many trailers are utilitarian and lack built-in living space.

Common types include light utility trailers, enclosed cargo trailers, flatbeds, boat trailers, and horse or livestock trailers. Heavy-duty variants, often called semi-trailers, are towed by tractor units and form a key part of commercial transport. The category also includes travel trailers and mobile homes, which combine dwelling space with towing capability.

Design features vary, but typical elements are hitch type (ball or other couplings), axles (single or tandem), braking systems (electric, hydraulic, or air), suspension, and load ratings (GVWR). Trailers require lighting and reflectors, safety chains, and secure cargo. Proper loading, tire sizing, and maintenance are essential for stability, braking performance, and road safety.

Trailers have evolved with road transport since the early 20th century. Regulations differ by country but commonly address licensing, maximum weight, braking, lighting, and inspection. In commercial use, trailers may require specific brake controllers, registration, and periodic safety checks. The term treilerit reflects Finnish usage for towed platforms in a global context.