We had those on our race jeep when we started...didn't care for them at all, except for the tough side walls. They're pretty low in the traction dept. in all terrain. They work well on the faster high horsepower trucks, because they don't want as much traction, especially on the drive tires. They need a lot of slippage so they don't tear up the transmissions on jump landings and whoop sections where there's a lot of off and on tire contact with the ground.
If you want the sidewalls to flex more when you air down, you need to let most if not all of the air out of the tires and drive around the block about 50,000 times to get them good and hot. The side walls will eventually "break in."
Your jeep looks sweet, BTW.
-Dan