Re-decking a trailer (wood bed on metal frame) is much easier with a screw designed to go through the wood then self tap into the metal without needing any holes drilled. The Hillman Group makes a screw to do exactly that:
The Hillman™ Group 1/4-20 x 2-3/4 In. Flat Head Self Drilling Screw with Wing - Phillips Drive (1 lb.)
The Hillman Group 47718 1/4-20-Inch x 2-3/4-Inch Flat Head Self Drilling