Steven Tyler has checked into rehab.The Aerosmith frontman - who claims to have been sober for 20 years since cleaning up his act in rehab in the mid-80s - is being treated at Las Encinas Hospital's drug rehabilitation clinic in Pasadena, California, for "substance abuse".Steven, 60, previously credited his film star daughter Liv, 30, and his Aerosmith bandmates for helping him recover from his previous alcohol and drug addictions.He previously said: "Four rehabilitation centres for drug abuse later, I've been able to take a long, hard look at my behaviour."Steven and bandmate Joe Perry - whose hits include 'Love in an Elevator' and 'I Don't Want to Miss a Thing' - were nicknamed the 'Toxic Twins' in the 80s.He is currently dating Erin Brady - who has a penchant for the rock 'n' roll lifestyle and was once thrown out of a casino hotel for brawling.The clinic at Las Encinas Hospital has been made famous by hit US TV show 'Celebrity Rehab with Dr. Drew'.