How many years or miles should a timing belt be changed on a 2000 V8 Tundra ?

Replace the timing belt at 90,000 miles or 10 years. Considering it is already 11 years old, replace it now. Warning: This is an interference engine. If the belt breaks you will have serious internal engine damage. The water pump is also driven by the cam belt so it is advisable to replace it at the same time you replace the cam belt in order to save labor cost later on when the pump fails. The pump will not last 180,000 miles so replace it now.