I was advised by my dealer to change belt at 60,000 miles. Service book on mine says 150,000 MILES. Decided to change it anyway. You should have seen the state of it. Wasn't another 1000 miles on it. Seems the tensioner pulley bearing was knackered and was throwing the belt againt the outside plastic cover .... it was worn down to 3/4 of an inch.
A very lucky escape ....