Can a company request you give back a portion of your time that you spend on a pre-trip and post-trip on your truck after hooking up and dropping out?

A company can always request almost anything but I think you want to know if they can just do it to you, right? Are you hourly, contract or paid by the run?

Are you over the road or local, are you paid miliage or hourly ? Do you drive their truck or your own truck.
Is there a contract or not ?