I did a search and found some information but not exactly what I was looking for (unless im blind!). when off road, i know that different pressures will be needed for different terrain, but what is a good pressure to start with? how do you know how low you need to go? how do you know when you've gone too low? does tire size have an affect? specifically i'm wondeting about my 33" PC MTs on 15" wheels. Should going in the mud have a higher pressure than going on rocky terrain?

also, what doy ou guys use to air back up? i know some of yall have onboard air which i'm sure is good, but i'm not that far yet. do some of you use just a little electric pump that plugs into cigarette lighter? thanks!

 

It'll take quite a while to do even 10psi but there's guys with CO2 setups that are much quicker but it'll cost a bit more.

 

IMO yes, but i dont do mud, lol. Iwouldnt go that low for "mud"
well I air down to 12psi. seems to work well for me, I know some people dont air down at all. I like the smoother ride, better traction etc.
As far as airing up, I use the Extreme Outback Its a little pricey, but VERY dependable, and Ill never ever run out of air, lol. I plan on hard mounting this at some point
but I recieved a 20# CO2 tank, and Im waiting on the regulator.
so Ill have both
PLEASE dont waist your money, Ive been there done that.

 

I think im fairly heavy and am still running puny 31's .... but they are Kumho's and have great flex, so i an get sidewall flex out of mine at 20lbs that most get out of there tires at 15 or below.

much less than 20lbs and i start loosing to much valuable ground clearance for the wheeling i do. (ya i know in need bigger tires...)

oh and i use a CO2 tank

 

I have a small compressor at home, has a good tank and all, could probably air up decently quickly. problem is, it runs off of ac power, so i guess i'd have to bring a power converter along as well to use that...

 

Deflators:
http://www.parksoffroad.com/miscinst...flatormain.htm

Inflators:
http://www.parksoffroad.com/miscinst...flatormain.htm

I run 33x10.50 Dunlops, which are load rated C. The first time I went out, I aired down to 20 psi, next time 18, next time 15 psi - WOW! That's the one - huge traction improvement. Guys I wheel with that have SuperSwampers or other bias ply tires don't even bulge the sidewall at 15 psi - they can go much lower (but rarely need to). One hof the Jeeps we ran with last time was at 4psi!

Tire size makes a difference due to the different sidewall height. You don't have to airdown a bigger tire as much for the same increase in footprint.

Mud is a tricky thing. It depends on the depth and consistency. Sometimes, you want as tall and firm a tire as you can get, other times you need the tire to spread out and flex to clear the mud.

I use the ARB compressor to fill my tires up. It takes about 5 mins a tire. If one of my OHTTORA peeps is feeling generous, I'll start filling mine with the compressor, then ask to use his CO2 tank when he's done. LOL

 

All I have is a mini that plugs into the cigarette lighter. It sucks, taking around 15 minutes to fill each tire. And it will overheat if you run it to long. I have to give it breaks inbetween tires, which is why I do not air down much. I will though when/if I start having traction problems. If I drop pressure, I go down to 10-12psi, and have never had any problems on any terrain. If it were quick for me to inflate, I would do it all the time. It is not, so I only do it when I have to.

 

Does anyone see any inherent problems with using the larger AC compressor I have with a cigaratte lighter power converter to plug it in to?

 

As long as your inverter can put out enough power to run the compressor, you will be fine. The one I have in my truck will only power small electronics. One time I tried to power a 4" Makita angle grinder off of it; nothing. The inverter I have on my work truck runs my 60lb electric jackhammer fine. Check how much juice your compressor sucks, and make sure the inverter can keep up.

 

To Air Down. Do all 4 Tires at one time to the EXACT same PSI. (Will even equalize all tires)

Roger Brown sells this as well.




Air Back up Attach to my DV 1050 12Volt air compressor and air up.



More here: http://www.mudrunner.ca/OBA.html

 

The pump that Michael (4Hummer) shows is something that a lot of folks here got about a year ago when Schucks/Parts America/Krager had a big sale. It's a great little pump, doesn't overheat, has good airflow, etc. If you can find one locally it's a good value even at non-sale prices.

Your idea with the inverter will be "fine", but it'll get to be cumbersome and end up drawing more power in the long run. AC inverters are very good at wasting electricity - be sure that you keep your engine running while using it.

Going down... the multi-air hose thing is cool, I have a similar setup to what's shown above, but it can be cumbersome to get things all connected and keeping an eye on the gauge. One thing though, it's nice to use when airing up as well.

If you're gonna be doing "this" (running off-road) a lot now, invest in something like a set of "Staun deflators". They screw on to your valve stems, release pressure to a preset point, and then stop. Very handy to just set & forget.


Pressures? I run at 15psi which is a good all-around starting point. You'll want a bit less for sand or rocks. Be careful that you don't go too low or you'll quickly learn the fun of "losing a bead" on the trail.