Always remember when your in position to overtake and asking for way. The person in vehicle ahead has view of road. there are many possibilities why he is driving slower or in wrong side. I can only name a few. for example, road condition, humps on roads where trucks are driven,, animal crossing possible, uneven bump on road, slower traffic not visible to you. Most of heavy vehicle are torque engines , they have to rev rpm to some point to stable torque, these are not some 500 horsepower engines that you touch gas and it goes to 200 plus in seconds. so you have be patient. that's it. when you show patience , you get your way at better moment.
