Unfortunately I was a truck driver for a number of years so I will give a little info you can bring up in a conversation, the truckers way of saying whats stated above is " floating through the gears". Atleast that how I have heard it called in my 8 years of driving.
Mention that the Pete (Peterbuilt) is the Harley Davidson of trucks. ( I know alot of you don't agree to this but he will, trust me.) Ask him if he takes the backroads to avoid the chicken coupes (scale houses). You could ask him if lot lizards (truck stop prostitutes) knock on the side of sleeper while trying to get some rest. Do not ask that in front of his wife or daughters. Say that you heard that car haulers are called parking lots on the CB.
Since your into car audio you can ask if he has a amp for his CB. Alot of truck drivers do have amps to make there CB's reach out further and walk over other drivers talking on the CB.
Then maybe talk more about his truck, because they are very proud of there trucks especially the Peterbuilt owners. Ask if he has invested alot on chrome for his truck, does it have a cummins or detroit under the hood. Is it a 9 speed, 13 spees or 18 speed. Most likely 13 or 18 since it being a Pete.
Bring up how sh!tty it is that truck drivers get a bad wrap all the time, but without truck drivers people would not have anything. Everything eventually is delivered by trucks. Food, everything in all supermarkets, stores in general, VEHICLES, materials to build your homes, concrete for roadways etc. etc. The truck driver doesn't get the recognition they deserve. Driving in bad weather, snow, ice rain, mountains, you get my point.
I could go on and on, but this should be enough to get you started. But top it off by telling him that thay should change the name of the truck driver to Professional Freight Relocaters. A little butt kissing goes a long way.