I do not know what springs my Jeep came stock with - 2012 Sport Unlimited with Max Tow. Mine is about as basic as you get. My goal is pretty simple really: 2" lift with 33x12.50/15s. I just want to do it so the ride is a little stiffer and it can still handle mild to moderate off road. No rocks around these parts to crawl on!
Daggo66 identified the part numbers for the stiffest factory springs as follows:
68004460AA - rear
52126319AB - front
See the LAST TWO NUMBERS (not letters) in each part number? They're "60" and "19," right? That's what folks mean when they say they have "19s and 60s" or "Mopar HD springs."
Now go look at the coil springs on your jeep. You can easily see them by crouching down near each wheel--they're the big springs that will be right in front of you. You'll see tags hanging off them that very clearly have numbers that look similar to the part numbers above. Read the last two numbers (not letters).
They probably won't be "19" and "60." With a 4 door, they'll probably be something like "17" and "58." If so, then going to "19" and "60" is unlikely to give you much boost and this is probably not a good option for you.
If, however, your existing numbers are something like "15" and "55" (numbers that are more common for 2 doors) then going to "19" and "60" will likely give you some boost.
How much boost? Well, click on
this link. That's my 4 door on 19s and 60s--
AND .75" spacers front and rear--sitting on the same 33x12.5R15 tire size you're considering. In other words, if you were to LOWER my jeep .75", you would see the results of having 19 and 60 springs in a 4 door with 33x12.5R15 tires.
Here's how those springs (and, again, .75" spacers) looked over stock tires.
In my opinion, that's not enough lift and, in fact, I'm adding a bigger lift in the near future. So my view is that the 19/60 spring swap is better left to the 2 doors.