72k or every 5 years, but 60k to be safeWhen should the timing belt on a 172 be changed? And how big a job is it...? It looks pretty tight in the engine bay!:S
yeah, best to get that changed aswel, the belt i think your referring to as 'tight in the engine bay'don't forget the aux belt to.
Rentech do the whole lot for 550 (cam+aux belts pulleys and bearings etc). goona book mine in for august soon. only done 30k in five years though !!!