Abstract: A fender liner for a dual wheel fender formed of epoxy-fiberglass and having a substantially flat top and an inboard side for attaching to a vehicle with bolts along the top of the fender on the inboard side. The fender liner is formed as an elongated flat panel made of sheet material with an inboard side flange. The flat panel runs substantially the length and breadth of the flat top on the inside of the fender for guarding the underside of the flat top against damage by rocks and other objects which may be hurled up against it. The fender liner is attached to the fender along the inboard side flange by the bolts attaching the fender to the vehicle along the top of the fender.