We recommend using contact cement. You have to cut the welt tail with pie shape cuts every couple inches in the areas that are curved. Install with the bead of the welt against the fender outer surface so that when the fender is installed the welt is snuggly pressed against the bed side. That way, it seals the opening and prevents mud and water from coming out through the gap between the bed side and fender. Be careful to prevent contact cement from getting on the outer exposed part fo the fender, as it may damage the paint. Masking tape will help here.
Mar-Ktech
