'Real Housewives' Son Arrested

More real life drama for the "Real Housewives of Orange County" -- this time, Tamra Barney's son is behind bars after cops made a major discovery during a minor traffic stop in the OC.

TMZ has learned Ryan Vieth -- whose traffic problems have been chronicled on the show -- was taken into custody Wednesday night after cops pulled the guy over ... and then learned there was an active warrant out for his arrest.

Law enforcement sources tell us Vieth had missed a recent court appearance in connection with a prior traffic problem -- so he became a wanted man.

Ryan is being held on $15,000 bail -- he's scheduled to face the judge later today.