What are the best gear and year to switch to for a 97 Dodge ram

 

Depends on tires and you don't need to switch axles

 

16 inch tires and I'm pulling with it would it be cheaper to buy or just regear I did some research they say my year only came with 3.21 3.55 or 3.92

 

Not rim size, tire size. They did only come with those gears but you can still regear. You are limited to up to 4.56 as that's the highest for your rear end (Chrysler 9.25) you can go. Regear would be your best bet because it will be new and you'll get 100,000 miles out of your new gears if done correctly. As you take a risk when buying used axles. Just remember the higher you go the lower your top speed will be and the more gas you will use, because your engine will go higher up in the RPMs. If you have stock tire size 4.10s should be fine.