[rappy93]

PHP код:

new TrailerID = CreateVehicle(450,-68.6366,-1132.4463,2.0863,63.8751,3,77,9000); // Trucker si remorca  
new vehicleid = GetPlayerVehicleID(playerid); // Asta este tirul tau. 
AttachTrailerToVehicle(TrailerID, vehicleid); // Iar cu asta vei putea atasa remorca la tir. 


I gave you some explanations in romanian, this should be all you need to attach the trailer to the vehicle.