I have a 2011 JK Unlimited Sport, I just got. I bought it with a 4'' Procomp short arm lift and trimmed fenders. I have 35's right now. Shooting for 40's. I realize this isn't as simple as wheels and tires. I plan on axle swaps and hydro assist before I do anything else, granted it will be piece by piece Anyone else running big tires that has any good advice? Looking at a prorock 44 front, and jockrock 60 rear at the moment. Thanks for any input.

 

Depending on what you want to do with it once on 40s, the ProRock 44 may not be upto it.

 

With 40s you want a wider than stock front axle and no more than 3 1/2 inch backspaced wheels. Otherwise, the size of the tires and wheel offset make it very difficult to turn sharply. So, you'll want to 60 front instead of a 44.

JK Unlimited's can get very heavy when modified, and as a result, you want to full float rear 1 ton axle.

You want to 1350 drive shafts, Hydro assist steering, and you'll need a good amount of fender well trimming.

 

I blew up a D44 ring and pinion with 37s on a light 2 door. Definitely go 60 front. Wide axles is good as well.

I'm going to 40s and using 2005+ super duty axles. 72" WMS to WMS. That's 6.5" wider than stock. Lots of room to play.

 

From what I have read the pro rock 44 has the same outer axle diameter as the 60, and the only real difference is the ring and pinion. I am looking at the complete axle with RCV's and ARB's. I am thinking pro rock 44 front because I am not running any real horsepower, lets be honest the stock 3.8l doesn't pump out the juice, Also I prefer to be under powered and over axled. I was thinking 1310's for the front and 1350's for the rock jock 60 rear. I would like to spin a joint before destroying anything else. I will look into full width options, turning sure is nice, I haven't picked out beadlocks yet, but they will most likely be 3.5's. I appreciate the input.

 

This is also an expo/crawl rig. I drive to where I am going to wheel and it will hopefully never see a trailer, so I have to be moderately street legal. I plan to take it to Alaska, and the Baja. I live in Oregon. Also on the hydro assist, I plan on getting that done with the axles, I have seen friends fight it with no hydro, and it's a must.

 

The front axle width is the issue of concern in order to be able to do a sharp full lock turn. You want as wide as possible.

I am pretty sure that the ProRock 44s are the same width as stock axles. If you run 40s with a stock width front, your turning radius will be about as bad as a crew cab longbed dually truck.

It doesn't make much sense to do a 1310 driveshaft with 40s unless you already own them. If you are buying new, do 1350s.

If you have a 3.8L automatic, 40s will suck for frequent highway travel--even with a supercharger and 5.38 gears. The engine rpm at highway speeds will be too low.

If you have a 6 speed, then you can get by with 5.38 gears. A RIPP supercharger works great with a 6 speed, 40s and 5.38s.

 

I do have the automatic and am going 5.38, I came from an 80 series Land Cruiser, and I can't imagine the power can be any worse on the highway. But I could be wrong, I would love a good hemi swap, but that easily pays for my axles.

 

Makes sense on the 1350's, might as well keep them both the same. I hope to eliminate the break factor by upgrading axles, but I do have a heavy foot. I just don't know if I can juice it enough stock to justify another 2 or 3k for a 60 front.

 

With 40s and 5.38s, and a 3.8L with an automatic, you will be turning about 2200 engine rpm at 70 mph. On a stock engine, that equates to about 75 rear wheel horsepower and less than 180 rear wheel torque.

75 RWHP and 180 RWTQ is not enough to turn 40s on a heavy rig.

To turn 40s and maintain speed on highway trips from Alaska to Baja, you need to be turning at least 2500 rpm at 70 mph with a supercharger, or you need to be turning closer to 2700-2800 rpm unmodified, with a Superchips or similar tuner at 70 mph (putting you closer to 110 RWHP and 200 RWTQ).

I'd suggest you go drive someone's automatic with a 3.8L and 40s with 5.38s before you make the investment in the axles, etc.