I know that for most of us, the last thing we think is going to happen four wheeling is to have a fire break out. However, exhausts catch brush on fire, wiring harnesses catch on fire, etc. The only way to put out fires like these is to have at least one fire extinguisher on hand. You also want to make sure that your extinguisher is rated to handle both electrical and chemical fires as these are the types that are likely to happen to a vehicle. These are usually denoted by having a "B" and "C" rating on the extinguisher.

Now, with that said, a lot of people mount their extinguishers in dangerous locations on their trucks. I've heard of people simply bungie cording them to roll-bars, etc. In the case of an accident or roll-over, these heavy objects WILL break free and possibly cause serious injury to someone if not properly restrained...just as your buddy riding shotgun will get the ride of his life if you hit something hard and he's not wearing his seatbelt.

I believe the best place to mount an extinguisher is behind the drivers seat as low down as you can get it. In this case, I bought a Kidde that includes a sturdy plastic strap that goes around the middle of the extinguisher and a clip to hold the neck of it. I simply drilled two holes into the roll-bar and used two self tapping screws to fasten the bracket to the roll-bar. Here's a pic of the bracket mounted to the bar.

Here's a picture of what it looks like with the extinguisher in the bracket.

I tried to rip the extinguisher from the mount with zero success so I know I'm not going to have "Killed by a Rogue Fire Extinguisher" on my tomb stone...

Also, remember to check the gauge periodically, as a discharged or undercharged extinguisher isn't much use.