I need to know if I would have to switch out my gears in my dodge ram if I put on 37" tires. I've been told that I would need to cause my factory ones won't hold up over time. If I do what ratio would be good, and can someone tell me what axle i have in my 2003 dodge ram 1500 4.7? Thank you!

 

Gonna be an expensive change. Whether it's warranted depends on your taste. If you want off-the-line jump, yeah, you'll need some 4.56s. As to the gears currently in place you probably have 3.92s or 3.55s. There should be a tag on the diff with a number on it: 3.5 or 3.9. Your driving habits will determine if this is a MUST DO.

 

37's are gonna be a hard turn for a 4.7L.

The biggest issue with tires 35" and over are the CV shafts. Also, you wont have clearance unless you have a good lift. (see wheel tire fitment sticky)

4.7L w/17's from the factory you likely have 3:55's. Most do.
There's a tag on your diff. It's stamped steel and will have your ratio. If you cannot find the tag or its unreadable, you can chalk your tire and chalk your driveshaft. With the truck jacked up, spin the tire one reviolution and count the bnumber of times the driveshaft rotates. Easiest to chalk the tire on the inside so you can see it while watching the driveshaft. That ro have a helper. The number of times the driveshaft rotates is your ratio.