The 2001 Mazda Tribute V-6 has a timing chain, not a belt. Because timing chains last much longer than belts; there is no published replacement interval. My experience with timing chains is that they gradually stretch over time, and to maintain optimal engine performance; they should be replaced sometime between 150,000 and 200,000 miles.
If an engine is operated in city driving, and idles a lot; the timing chain should be replaced sooner than the chain on an engine which is mostly used for freeway driving. So I would select the mileage within the above range which corresponds to the usage type.