That comment is not entirely true. It depends on the application.
Leaf spring design (as well as longer perches) can GREATLY affect spring wrap.
I remember being able to send my rear yoke into bind with the stock leafs on our XJ years ago. (just on dry pavement) Simply swapping in a set of OME leafs cured that. That was running 31's though.
Of course, the bigger the tires you run, the more weight on the rig, the amount of throttle applied and the bigger the obstacles all play a part in how much spring wrap you'll get with a given leaf pack.
We run 35's, locked up and play in big rocks with our XJ's. Our new TrailGunner leafs (7-leaf pack with anti-wrap clips) are PLENTY substantial for wheeling this set-up with no traction bar. Sure, there's a BIT of wrap on bigger obstacles, but nothing that causes yoke bind, hopping or loss of traction.
Now if youre running an extremely heavy rig on one tons and 40" tires, you've basically left the norm of what you'd consider most (dual-purpose) XJ's to be. At that point, you are easily into lots of custom fab, uni-body re-inforcement, etc and a traction bar would most likely be mandatory.
One of my guys is running a traction bar on his XJ with 37's, but he flipped the rear springs. Because of the center pin location, that's instant spring wrap.
As Jason can attest, it's not real easy fabbing a traditional traction bar on an XJ. The one Alex did works fantastic, but involved cutting out a good sized section of the floor and fabbing a crossmember/mount to do it.
That rig doesn't see street duty though.
For the vast majority of guys that are running 33-35" tires, there are springs that are perfectly fine without a traction bar.
