2.5 inch lift. What size tires?

Without doing fender mods, 33" tires should be your max (you should have 30" now with those wheels). You'll need either a narrow tire (10") or add wheelspacers to fit the normal 12.5" wide tires.

Keep in mind that if you have a 4 cylinder motor, you'll have a rough time on the highway. Even with a 6 cylinder, you'll feel the bigger tires trying to get up to speed and going over bridges and hills. The only real solution to this is replacing the factory axle gears with smaller gears (numerically higher... like 4.56 for 6cyl or 4.88 for 4cyl).

You will have over 4 inches of lift. 33's will be no issue and 35's would fit with a little trimming. If those rims are 8" wide you can go with a 12.50 wide tire but the back spacing might let it rub. A spacer or cheap steel wheels would fix that.