Hi everyone.   I did a search and couldn't find an answer specific to my question.    I finally got my new, first samurai out for a real weekend ride.    I have an 88 Samurai, with a spring over lift, and 31x10.50's.   Had my wife and 2 kids in it on the first run and we were really happy with it, but it was pretty rough.   So I aired down the tires to 16 p.s.i. and what a difference, felt like I changed the suspension.    After looking at the tires they weren't even bulging, so I dropped them down to 14 psi.   This was all I dared drop it, as I had to to tow it home about 50 miles.   Still even at 14 pounds, the tires still looked like they were full of air.

My question is  How low can I drop the air pressure in the tires and still have good performance?   I live in Utah, so I'll mostly be in the mountains, with washboard roads,  rock and hard packed trails.   Also, how low can the tires be and tow safely?    3rd question is, if it's not safe to tow them low, and no service stations are close, what are y'all doing to fill the tires back up?    Is there a cheap compressor you use or something?

Thanks in advance.
fixed.

I drop mine to 10-12psi on the trails.  FYI, on one of my rigs with 31x10.50s I'm running 15x8 rims.  I've never had any lost bead problems at that PSI, and the tires still appear full on a lightweight Samurai.

What you need is a good quality, air compressor to air the tires back up to 20 psi for the tow home. 
 
These work really well and I've used one for five years.

http://truckandwinch.com/smittybilt-mv50-heavy-duty-air-compressor.html

I have three of the MV-50's they are a good air compressor, the only thing I had to do to mine was to pull the black cap off of the end of them with a small Allen wrench and solder the two wires together, they have a crimp on them that that is so weak you can pull them off with your fingers, there is a 60 amp relay in there also and a 30 amp in line fuse, make sure you have your engine running when you use it, or if your battery gets low you might blow the fuse.

I forgot that I had to do the same thing-solder the wires together.  The crimps on mine pulled out too.

Stock tires are 205/70R15 which is about a 26.3 x 8" tire. Stock tire pressure is listed on the plate at the left side of the dash.  Mine says 20 PSI unladen, and 26PSI (rear) laden. Your tires are MUCH larger, and can go (much) lower.  It's mostly a matter of maintaining the correct, flat footprint (tire patch) on the paved road surface.  To minimize the likelihood of losing a tire bead at the really low pressures used on the trail, aim for a rim of the correct width for your tires, typically 2-3 inches narrower than your tires' section width. It's best to look it up on the tire manufacturer's website. The factory engineers are the best source of knowledge for their own tires. As an example, my BFG TAs in the the 31x10.5 size call for a 7-9" rim width. Most folks would choose an 8" rim.
  
A popular cheap 12V compressor is the MF-1050 / MV50.  Google around and you'll find plenty of discussion.  I bought a HF cheapo, similar to their #66399, and it has served well, but my needs are simple. Viair has a great reputation with a wide and deep product line, but is more expensive. Wiring [from the compressor] to the battery is frequently a weak link and you may have to "improve" it. I've successfully used two-conductor low-voltage [direct-burial] landscape wire from Home Depot, in the heavier gauges.  Plan to run the engine so that the battery will be charging (higher voltage) while the compressor runs. There's a lot of voltage drop in the standard long (skinny) wires and the better, faster compressors draw around 30Amps.  If your compressor has a fuse (a good idea), be sure to carry a spare or two with the compressor.  [Edit 2: LowRangeOffRoad has the MV50 compressor for $60 including free shipping -- possibly the best deal going anywhere now. There's several easy How-To's on the 'net for increasing its performance, if you're at all handy. ]
 
Edit1: There's a great article on "Tire Pressures for 4-Wheeling" at: http://www.4x4now.com/sfjun96.htmtire
I own a couple of his 4WD books.  Ecological 4-Wheeling Adventures is no longer in business, so visit the site now while it's still up for all to enjoy -- www.eco4wd.com.

I run ProComp MT 31x10.5x15's on my Sidkick. At the "recommended" tire pressure(28psi) the ride was very rough and only the very center 1/3rd of the tire tread was wearing, I dropped the pressures down to 20psi(ish) and the ride greatly improved and wear was now 2/3rd's of the tread width, I had to drop the tire pressure down to 16 psi front and 14 psi rear to get the PROPER wear pattern. BUT the DD mileage really suffers!!!! On the trail tire pressures had to be around 8psi front, 6 psi rear to get crawling traction.

There is only one real option, and that is to have a portable air compressor/tank for pavement towing/driving.

Thanks for the replies everyone, I really appreciate it.