depending on manufacturers, it ranges from 70T to 100Tkm. i just changed mine at 75Tkm, and the belt still looks good. timing belt replacement is a very cheap thing to do, but if it breaks on you, it will cost you a whole lot!
Yup mas matagal nga ang timing chains sa timing belts, pero ang mas matibay kung timing gears. Pag binababa lang ang makina tsaka lang pinapalitan itong gears.
Timing gear type is only one type of design sa engine. Meron belt, chain at gear ewan ko kung meron oa iba. usually mga us cars lalo na yung mga luma gaya ng ford taurus. made of special plastic coated ang gears nito para di maingay. vespel ata ang material.