Tips on changing lanes

I have used these tricks to judge where the rear of the 5th is. Sometimes you are able to use the shadow created by the trailer to tell where the end is and the vehicle you are passing. Also take you vehicle out on a highway and count how many dashed lines long your vehicle is. MOST roads use the same spacing but don't count on it, use one or two more than you counted. Put that number in your memory as how many to have visible in the mirror before pulling back in. I also put a short "curb feeler" with a highly visible flag on the curb side of the rear bumper to give me an idea. So if you find one of these tricks work - use it, I don't own it. :)