I have a JKU on 37" BFG KM2's.
ATX wheels without beadlocks.

I ran about 8psi last weekend in deep snow without drama.
That seemed to work well and I never had an issue with traction or floatation.

Guys with beadlocks were down as much as 3psi.
That seemed to be even better I the deep snow.

How low can I go before I have a real risk of losing the bead?

 

I have 12.5x35's on 15x8s and find that I increase the risk of loosing a bead if i go below 12 psi. I have wheeled successfully at 8 psi, but I have also lost my bead at those pressures. I have yet to lose a bead at 12 psi.

But that said, you have to take into account your tire size coupled with your wheel size. So what works for me, may not work for you.

 

I have went down to 4psi in the sand dunes without losing the bead on my stock rubicon tires & wheels

 

Did a snow run few weeks ago,most guys were running 1/2 to 1-1/2psi their tires without problems.I myself ran 6psi down from 8psi

 

I run 35s on stock Moabs and in snow I've been down to 4-5 PSI with no issues. Snow is very forgiving. Mud and rocks are another issue - I usually stay at 15PSI in that case.

 

It also depends on your wheel width, weight of the vehicle and the conditions you're in. In the snow (and sand) you can usually go lower than you normally would. When I had 35-14.5 boggers without beadlocks on my old XJ, I ran as low as 1.5-2 psi in the snow without loosing a bead. I also ran at 8-9 psi at Elbe during the spring and lost beads several times.

 

do you guys mind explaining loosing a bead to a newb?

tire coming out of the rim allowing air out, I assume?

 

That's an open ended question. So my answer is never or possibly every time you go wheeling. Really depends on too many factors. Just watch how sharp your turning the wheel when aired down, and don't air down below 12 psi.

 

Yes, you're correct -- a tire popping off the lip of the rim.

This happens when there's a side force on the tire while the pressure is too low.
Happens much less when there's little grip on the surface (e.g. soft sand), unless making fast turns, which bend the tires sideways.