When should Timing Belt be replaced?

Lexus recommends replacing the timing belt on the 3.0L V6 every 90,000 miles or 72 months (6 Years)

It should be changed at 90,000 miles unless its driven in severe conditions(excessive idling or low speed driving for long distances) If it is v v t-i engine it is an interference engine and it will bend valves if not done at proper time. If its not a v v t-i it will just break the belt. Good Luck Beverly