The off-road folks I ride with operate mostly in the VHF radio range. Some operate in the UHF in the 462 Mhz range or FRS. There are about 20 or so VHF channels apparently approved for our use and they're in the 151 - 157 Mhz range. There are charts showing which freq's are used in various parts of the country to avoid stepping on other users.
Many of the RZRs and CanAms have some elaborate radio/intercom systems costing a few grand. No one I know has a radio license and I don't see why these radios wouldn't be used by truckers as they've got decent range, excellent clarity, and they're danged cheap to purchase. My radio cost me $35 on Amazon and is the size of a pack of cigarettes.
I read truckers use channel 7 but not sure the freq.