My truck a 2002 D/A CC is equipped with Revo tires. While towing on an extended trip I began hearing what sounds like drivetrain noise. What is a good method to determine if it is the drive train or the tires making road noise?

change the tires back to stock or known quiet tires

That's a good idea. Why didn't I think of that. I thought maybe there might be a tech who could tell me how to really diagnose the problem instead of parting out the truck like the dealers do.