NoChain,

Depending on how heavily loaded and how fast you are riding the T's "main tank" of nominally 4.2 gallons will get anywhere from 90 to 140 miles before the rider has to switch to the 0.6 gallon "reserve".  Riding fast (75-85 mph) one-up at freeway speeds you may get 110 miles before switching to reserve.  Riding the back roads you will probably get 120 to 140 miles depending on how hard you are on the throtte before running below the petcock's vertical input tube which constitues the main tank.  By taking fuel in the horizontal side petcock tube you should be able to get 25 to 35 more miles before the tank and carburetors are really empty. 

Besides the advice Stan gave you about filling up the carburetor bowls another help is to put on full choke whenever you have run out of gas.

Fred