If I go with 37 X 12.50 will i have to change the gears in my 99 2wd dodge ram 1500 5.2 magnum and if i do whats size do you prefer.

 

You don't ever HAVE to change you gears. However ... if you're going to put 37's on ... it's probably a good idea. What are you wanting to use the truck for?

 

why so big on a 2x, are you trying for 200mpg?

 

just a evryday driving truck/ show truck

 

4.56 ... don't think 4.10's will get it done.

 

I run 37" ProComps. I still have stock 3.55s. The truck drags *** a bit in overdrive. But in 4-LO I have no troubles going where I please. But if you are running 2WD with no low range options, I would go 4.56 minimum...possibly 4.88s

Just my 2 cents

 

If you're running 3.55 gears with 30's ( I don't know what 2WD tire sizes are):

3.55 gears X gears
----------- = --------
30" Tires 37" Tires

Where X would be the theoretical equivalent to what you are currently running. That means that (3.55/30)*37= 4.38. As everyone knows, there are now 4.38 gears. This is just a hypothetical equivalency. Bear in mind that the tires will weigh more, so you will probably want to adjust for this extra drag. Taking all into account, I would suggest 4.56 gears. Running 4.56 gears on 37" will give you the following equivalency:

4.56 gears X gears
----------- = --------
37" Tires 30" Tires

Now X represents what gear you would have been running with the 30's. (4.56/37)*30= 3.70. Again, there is no 3.70 gears. All this tells you is that running 4.56 with 37's would be the same as 3.70 with 30's. Remember, there is no weight factored in and this is all theoretical. Just for kicks:

4.88 gears X gears
----------- = --------
37" Tires 30" Tires

This equation gives an equivalency of 3.96 gears with 30" Tires. Initially, I thought that 4.88 might be too low, but there is additional weight and 3.90 is a ratio that these trucks had.

Some of this is trivial, but I hope it gives you some idea. Good luck and I think it's nice to see some lifted 2WD's for a change.