When would I need to change the timing belt for my car?

I have a nissan sentra its not new we've had it from 2002 (new then)

umm and just wondering how many years untill we should change it or how many times a year if that is nessacryWhen would I need to change the timing belt for my car?
All of the 02 sentra models I looked up have engines that use timing chains instead of a timing belt..it shouldn't need replacing until the engine needs to be rebuilt%26gt;When would I need to change the timing belt for my car?
The interval varies by car. Normally it's 80,000 or more. Some cars are a little less. Make sure you have a belt and not a chain because chains don't need replacing unless there's a noticeable difference in the performancee of the car. Look in the service manual, call the dealer and ask, or search the Internet and hope.