i have a 2001 toyota Rav4, when should i change the timeing chain, has 160,000 miles

Your year model has chain,and it doe,s not have to be changed,unless you here it rattling,or here noise from it.If you here any thing,then yes i would change it,some time,s the idler,s wear out,but like i said ,if you don,t hear anything,you are ok.

That engine is pretty bombproof, shouldn't require that kind of maintenance for quite some time