ROCK legend STEVEN TYLER called off his engagement to fiancée ERIN BRADY because he feared her wild-child ways would resurface to push him right off the wagon.

That’s the shocking REAL reason behind the 64-year-old Aerosmith front man’s decision to call off his wedding to the 39-year-old former tour accountant.

“Both Steven and Erin have long wrestled with addictions to drugs and alcohol,” an insider told The ENQUIRER. “They’re both clean and sober for the time being, but Steven’s not taking any chances with temptation.

“They’ve been co-dependent in the past, and he’s worried that if she slips so will he. He has Aerosmith tour dates running throughout November and mid-December and he doesn’t want any distractions.”

But that wasn’t the only problem, reveal sources. The band reportedly   

does not like Erin, and Steven doesn’t need the drama of having her on the road with him.

The twice-married performer and former “American Idol” judge began dating Erin in 2006 after Teresa, his wife of 18 years and the mother of his two youngest children, left him for their contractor.

Insiders told The ENQUIRER that Erin had been push­ing Steven to the altar and he didn’t even tell his family when they got engaged over the Christmas holiday in 2011 – because his relatives don’t like her, either!

Once Tyler quit “American Idol” and returned to Aero­smith, “the band told him he had to choose between them and Erin,” said the source.

“Right now, he’s chosen his group. But Steven still adores Erin and hopes that they can get back together down the road.”

Meanwhile, Tyler’s camp has denied a split, saying: “Just as any couple goes through trials and tribulations in a relationship, Steven and Erin are asking for their privacy at this time.”

But the strain of THEIR “tribula­tions” seemed evident on Nov. 2 when Aerosmith performed on the “Today” show. Steven not only forgot what show he was on but was also overheard on-air screaming to the crowd: “Thanks for coming out, you crazy f***s!”