Have you tuned the antenna?
Is the noise consistent with engine noise?
How is it wired?
Can you squelch out the static?
The lower end CB's use less filtering to save money so you'll have a higher noise to signal ratio than with a higher quality rig.
"But it does me no injury for my neighbour to say there are twenty gods, or no god. It neither picks my pocket nor breaks my leg." - Thomas Jefferson, Notes on the State of Virginia, 1782
Arguing with a truck driver is like wrestling with a pig in mud, eventually you realize the pig enjoys it.