In case you have been living in a cave these last few years and haven't noticed, bead-lock wheels are the "in" thing. A special flange is either welded to a production wheel, or made as part of it during manufacturing. An outer ring is then bolted to this flange. The tire's bead is captured between the outer ring and the flange. This makes it impossible for the tire's bead to become unseated when the tire is run at lowered air pressure.
In all but the most extreme cases, bead locks are only used on the outside edges of a wheel because this is the side that takes the most side-loading. Picture your vehicle on a sidehill-the weight of the vehicle is transferred to the low side, causing that tire to want to roll away from the bead seat on the outside. On the inside, the tire is pushing against the bead seat. OK, you're right, on the high side, just the opposite is happening; however, the side load on the tire is greatly reduced and only in extreme situations does a bead ever become unseated.
All sounds great, right? Well, there are some drawbacks. Let's take the mounting of tires first. Be prepared to mount the tires on your bead-locked rims yourself-that is, unless you're really friendly with the local tire shop, as most aren't going to touch them. Most likely, they will quote a liability issue to you. However, bead-lock wheels are really fairly easy to mount at home, although an in-lb torque wrench is a necessity. Time is the factor.
With the locking ring removed, you push the tire over the bead-lock flange and roughly seat it against the opposite side of the rim. A bit of tire lube or soap helps. Next, lay the locking ring against the tire's bead and fasten four or more of the supplied bolts 90 degrees apart. Depending on the design of the locking ring, you may have to temporarily use some longer bolts to get the ring started. Put in the rest of the bolts and torque them down in stages using a criss-cross pattern. Use the manufacturer's torque specifications, or 20 lb-ft or 240 in-lb for a 5/16-inch bolt, and 35 lb-ft or 420 in-lb for a 3/8-inch bolt, assuming that they're Grade-8 bolts (with five lines on the head) and lubricated with engine oil. You're going to have to go around and retorque them at least four or five times. I like to use an in-lb torque wrench, as I have found them to be a bit more accurate than a lb-ft torque wrench when it is used at the bottom of the scale.
Balancing bead-lock wheels is a bit of a problem, as the ring won't take clamp-on-style weights-which is no big thing, as those usually get knocked off anyway. So, all balancing is generally done from the inside with stick-on weights. Again, you've got to find a tire shop that is willing to do this.
Flat fixes? You're pretty much on your own. But usually you can just take the lock ring off and get your hand inside the tire to install the patch without having to take the tire completely off the rim.
Maintenance? Depending on design, the bolt heads may get snapped off by a rock, but this is rare. However, if it does happen, you need to replace the bolt as soon as possible. This is important, because without the bolt, additional load is being transferred to the other bolts and additional failures may take place. Yep, it's a real pain. The easiest way is to drill the appropriate-size hole in the bolt stub and insert an "easy out." The second method is to remove the bead-lock ring (please don't forget to deflate the tire first) and pray to the rim gods that there is a short stub sticking out that you can grab with some locking pliers.
Legality? Everyone will tell you that bead locks aren't DOT-approved and therefore not street-legal (there are a few that claim to be approved). However, as far as I have been able to research, there is no DOT standard for bead-lock wheels. There may be other items that you're using on your rig that aren't DOT-rated, such as aftermarket seats, competition-style seatbelts, and fuel cells.
If an officer of the law should stop you, and tries to write a ticket for your bead-lock wheels, can he really tell if they're poser "street locks"? Some of the ones I've seen sure look like the real thing. And what section of the vehicle code, or the Health and Safety code, is he going to put on the citation? "Unsafe vehicle"? That would be a tough one to prove. Probably the best thing to do is just say something like, "Yes, officer, I have a set of street tires and rims that I normally run and will put them on as soon as I get home." The only foreseeable problem would be an accident where it could be proven that wheel failure was the cause.
Do I use bead-lock wheels? You bet. In fact, I have more than one set.