new to this truck thing w/a 95 ranger

just wanted to introduce myself i have 95 ranger long bed that i got cheap ($1500) in bad shape no airbags, whole in radiator which i patched nicely and i just finished the stereo clarion cassette/6cd changer remote control, 6x7 pioneer in front and cheap 6.5 audiovox as complement on the back sounds ok, i'm gonna add an equalizer a cheap one and i'm done
as for more power i'm gonna go w/ a flowmaster or magnaflow muffler and if you have any other cheap ideas are welcome
where i need help is in size tires, no lift i want the truck to tow my dirt bike
i have a set of 16' aluminum from my eclipse w/ the same bolt pattern, how big can i go with the tires
i don't have a lot to spend on the truck because my talon is my spoiled child but i can't just leave it stock so any ideas
sorry for the long post
thanks