What Are Roof Rails?by Mike Davey
Roof rails are a common sight on modern vehicles such as SUVs and mini-vans. Roof rails run along the length of the vehicle's roof. Their purpose is to provide an attachment point for crossbars and other devices designed to secure loads carried on the roof of the vehicle. Roof rails are attached to the vehicle's roof by feet or other mounts. This is one attribute that distinguishes roof rails from other attachment devices, such as tracks, which are typically built directly into the roof of the vehicle.
Roof rails are usually one of two types. The first type resembles a long, inverted "C." In this type of roof rail, the feet of the roof rail are attached to the roof of the vehicle, and the rail itself forms an arc. This type of roof rail typically has several inches between the roof of the vehicle and the rail. The second type is the flush-mounted roof rail. There is no space between the rail and the roof of the vehicle in this type.
Vehicles are equipped with roof rails to simplify the attachment of various kinds of roof racks and carrying systems. Roof rails are not themselves a roof carrying system. Roof rails instead provide a stable mount to attach other load carrying items, such as crossbars or towers that can be used to carry various loads.
Aftermarket roof rails are available from some manufacturers. These roof rails come in a variety of lengths to suit various vehicles. Aftermarket roof rails must fit the vehicle for which they are intended. Some manufacturers offer a sizing guide to ensure a good fit. Some aftermarket manufacturers also offer roof rails designed to mimic the roof rails produced by the original equipment manufacturer.
Roof rails cannot be installed on all vehicles that lack them, as some cars and trucks use alternative mounting systems such as T-tracks or fixpoints. A T-track is a channel or slot running the full length of the roof. Fixpoints are mounting points located on the roof of the vehicle, often concealed by sliding flaps. Some roof racks do not require any sort of installed mounting point, but are clamped directly to the vehicle's bodywork.
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