Airing down, When and why

bugnout · **Posted:** Tue Mar 04, 2008 3:02 pm

Here's my philosophy, disagree or agree, I'd like to hear your thoughts.

Just went on a trip to Badlands and everyone in the group was airing down, even the guys with no lifts and stock tires. In the balance, I think ground clearance is more important than the traction gained from airing down. If you've got plenty of clearance, by all means air down, but for most of us driving KJ's I think ground clearance is more important. I did mention it, but was overruled by the trail leaders. Felt like it was a point of religious belief.

Typically I run my MTR's at 40psi on the road. Off road, if I'm going to be doing trail, hill climbs and some mud, where there aren't a lot of rocks to crawl over, I leave about 28 pounds in the tires. I feel that ground clearance is the most important factor for my KJ for this type of offroading. I don't feel I've reduce my capabilities at all on any trip.

I've only been to Moab once, but once was enough to understand the value of airing down for rock crawling. I think airing down to about 18 pounds for those conditions is about right. I will loose about an inch of ground clearance, but much better traction and can really use the side walls.

I also think that if I really need the extra traction you can always let more air out, but typically your going to banging the skid plates a bunch if you start air'd down.

I'm from the church of ground clearance, All opinions welcome,

tjkj2002 · **Posted:** Tue Mar 04, 2008 3:27 pm

bugnout wrote:

Here's my philosophy, disagree or agree, I'd like to hear your thoughts.

Just went on a trip to Badlands and everyone in the group was airing down, even the guys with no lifts and stock tires. In the balance, I think ground clearance is more important than the traction gained from airing down. If you've got plenty of clearance, by all means air down, but for most of us driving KJ's I think ground clearance is more important. I did mention it, but was overruled by the trail leaders. Felt like it was a point of religious belief.

Typically I run my MTR's at 40psi on the road. Off road, if I'm going to be doing trail, hill climbs and some mud, where there aren't a lot of rocks to crawl over, I leave about 28 pounds in the tires. I feel that ground clearance is the most important factor for my KJ for this type of offroading. I don't feel I've reduce my capabilities at all on any trip.

I've only been to Moab once, but once was enough to understand the value of airing down for rock crawling. I think airing down to about 18 pounds for those conditions is about right. I will loose about an inch of ground clearance, but much better traction and can really use the side walls.

I also think that if I really need the extra traction you can always let more air out, but typically your going to banging the skid plates a bunch if you start air'd down.

I'm from the church of ground clearance, All opinions welcome,

I would have to disagree.I air down all the time when offroading.You got skids,use them,I do all the time.Airing down gives you a better ride offroad,better traction(by increasing the tires footprint).

The 1/2"-3/4"(I only loose about 3/4" going from 42psi to 12psi in my Trxus MT's) of clearance lost is nothing compared to the added traction those aired down tires give you.Stock wheels and tires I wouldn't go under 18psi.If your running tires like MT/R's going down to 12psi will not hurt anything.I usually airdown to 12-15psi when I offroad(depending on the trail,lower psi for more extreme trails).And tires like MT/R's need to be aired down low to work properly offroad,just don't get stupid with the speed and turning.Heck I ran 28psi as a norm on long road trips when I still ran MT/R's,lowered my tires hieght for better power in those mountains and passing.The KJ is a rather light vehicle compared to others and MT/R's(and the like) are made for heavy vehicles.

WoodysKJ · **Posted:** Tue Mar 04, 2008 4:00 pm

So along the airing down theories, What9 assuming everything else is equal) a decent pressure for NON beadlock rims? I was always under the impression that beadlocks were a must if you air down a bunch. I can see where it would be a real witch to air down and then break a bead while wheeling. Where is the balance?

scarletbegonias · **Posted:** Tue Mar 04, 2008 4:23 pm

air down/fill up ..that's all we do here on the coast of jersey! here's a video about tire pressure that someone posted awhile back on one of the nj surf fishing forums
((fyi the video's kinda tacky BUT it's informative!))

http://www.youtube.com/watch?v=-9UNFgMXSYQ

tjkj2002 · **Posted:** Tue Mar 04, 2008 4:31 pm

WoodysKJ wrote:

So along the airing down theories, What9 assuming everything else is equal) a decent pressure for NON beadlock rims? I was always under the impression that beadlocks were a must if you air down a bunch. I can see where it would be a real &^%$( to air down and then break a bead while wheeling. Where is the balance?

It'll vary on what you think is good enough.I air down to 12-15psi with my Trxus MT's and never had any problems(no beadlocks either),I know RL airs down to 10psi with his 35" MT/R's on his XJ and never had a problem(no beadlocks either).Below 10-12psi is where you'll need beadlocks,this is only for MT tires,AT's keep the psi a little higher(14-18psi),and stock tires and all those other car tires(street tires) I wouldn't go lower then 18psi.Those are just in my opinion.

bugnout · **Posted:** Tue Mar 04, 2008 4:39 pm

tjkj2002 wrote:

It'll vary on what you think is good enough.I air down to 12-15psi with my Trxus MT's and never had any problems(no beadlocks either),I know RL airs down to 10psi with his 35" MT/R's on his XJ and never had a problem(no beadlocks either).Below 10-12psi is where you'll need beadlocks,this is only for MT tires,AT's keep the psi a little higher(14-18psi),and stock tires and all those other car tires(street tires) I wouldn't go lower then 18psi.Those are just in my opinion.

I popped a bead on this last trip and was running 28 psi. Don't think it was a psi issue, It had been my spare until two weeks ago when I rotated it into the 4 new ones. It was mounted 4 yrs ago and hasn't seen the road till now. I'll go 14 lbs next time and see how I like it. Still in the church of ground clearance, but willing to flirt with being a heretic.

Tokyojoe · **Posted:** Tue Mar 04, 2008 4:44 pm

The ride comfort difference is HUGE! But think about the bounce when you hit a hard object. You can bounce pretty good and with more speed, you bounce higher. Easier to puncture a higher PSI tire, off-roading. Tire has no give. Now you have a flat to deal with.

pixeldzn · **Posted:** Tue Mar 04, 2008 4:45 pm

Man, that's gotta be a bumpy ride with 28PSI in those tires offroad.

I air down partly because of comfort, partly because of traction. You want your tires to bend around bumps and rocks and tree stumps, not bounce over them.

I take it you didn't spend much time in the sand dunes at the Badlands. Too much tire pressure and you just dig a hole - I know from experience :lol:

AndySRT · **Posted:** Tue Mar 04, 2008 4:51 pm

i have learned in my 5-6 years of off roading to air down all the time. I usually go about 15psi. it has helped me get up obsiticles after airing down that i wasnt able to get up without airing down. but its personall choice I do it because i know my skidplates are there for that reason to be used and they have gotten quite a bit of use showing off what the KJ can do. :lol:

bugnout · **Posted:** Tue Mar 04, 2008 5:19 pm

pixeldzn wrote:

I take it you didn't spend much time in the sand dunes at the Badlands. Too much tire pressure and you just dig a hole - I know from experience :lol:

No, I've spent lots of time in the kitty litter. Never got stuck, Thats one of the reasons I don't air down so much. I don't have any bad experiences yet to sway my belief. Maybe I'm a bit cautious though, staying out of area's that look a little too soft. Maybe just lucky.

I have to confess, I haven't aired down at Badlands on the advice of the guy I went to Moab with. He's got years of experience and planted the basis for my faith in not airing down for terrain like at Badlands. I think he'd be the first to agree with all your points, and he always airs down his TJ. His reasoning for my situation makes sense to me, and so far has not been contradicted by experience.

Rock Lizard · **Posted:** Tue Mar 04, 2008 5:32 pm

Like Troy said, I run my 35's at 10 PSI, and I have 15x10" non beadlock rims. 15x8" rims would be much better for running that low of PSI without beadlocks. When I had 35's on 15x8's I ran 6-8 PSI without ever having a problem. A much bigger footprint helps a lot, but if you notice, most tires suited for offroad, even BFG AT's, have tread that extend down the sides of the tire. When you get into bigger rocks, you will find sometimes using the tire footprint just doesn't grab enough, so you get a lot more grip and traction using the shoulder and sidewall of the tire. This is where the tire really conforms to the surface of what you are crawling. MT/R's are awesome to watch in the rocks when aired way down, because I have seen many times where the side wall will twist well over 90* to wrap around a rock and not cut, tear or break the bead. Airing down on trails will actually prevent a lot of damage to the tire, because the tire can flex over an object, such as a sharp rock or stick/stump. If you take two balloons exactly the same, air one up just enough to be squishy, and the other so it is full and tight, and poke them with a stick, I gaurantee the full balloon will pop first everytime when using the same stick and the same pressure applied to the balloon. I'm not exactly sure the reason why people are so scared to air down, other than not wanting to take the time to air down and air up. It scares me more to see people running anything more than 15 PSI on the trails we run here. It's just a sidewall puncture waiting to happen and the traction is no where near what a deflated tire has.

So the air down "nazis" are actually trying to save you time and money, not inconvenience you with having to spend 15 minutes to air down and refill your tires. Hope that helps explain a little bit of the importance of airing down. Most of you guys are running 16x7/8" rims with 245 or 265 tires. You can easily run 12 PSI on those tires and actually be less likely to pop a bead. Ted found out on a large rocky hill after tearing off a valve stem that a tire with no air in it has incredible traction. :twisted:

bugnout · **Posted:** Tue Mar 04, 2008 5:40 pm

Rock Lizard wrote:

Airing down on trails will actually prevent a lot of damage to the tire, because the tire can flex over an object, such as a sharp rock or stick/stump. If you take two balloons exactly the same, air one up just enough to be squishy, and the other so it is full and tight, and poke them with a stick, I gaurantee the full balloon will pop first everytime when using the same stick and the same pressure applied to the balloon.

Now that does make sense. So we are protecting the tire by airing down. I can buy that argument.

nlife · **Joined:** Thu Aug 16, 2007 11:43 pm **Posts:** 226

Rock Lizard wrote:

I'm not exactly sure the reason why people are so scared to air down, other than not wanting to take the time to air down and air up. It scares me more to see people running anything more than 15 PSI on the trails we run here. It's just a sidewall puncture waiting to happen and the traction is no where near what a deflated tire has.

I don't air down because I don't have a way to inflate the tires on the trail after I'm done

. I wouldn't want to run 12 psi on the highway for whatever distance it takes me to get to a station - usually about 60 km. Although, I don't think I do the same type of trails most of you guys do. My wheeling is usually limited to deactivated roads and a few ditches. Other than that, I'm on fairly well maintained FSR and not climbing through rocks or anything extreme.

N

LibertyFever · **Posted:** Tue Mar 04, 2008 6:51 pm

I must agree that airing down a "stock" Liberty means you'll be hitting every single rock on the trail which negates the extra traction. When I get a modest lift and taller tires on my Liberty I'll try airing down again.

On my YJ I run about twenty-two pound on the highway and much less on the trail. I air down to increase the footprint of my tires and increase their flex. In the winter when I want to ride on top of the snow I'll air down as low as four or five pounds but then there's the risk of popping a bead (been there, done that, got the T-shirt

)

JIMMY JEEP · **Posted:** Tue Mar 04, 2008 6:54 pm

nlife i got this to help when airing up/down
http://www.lostjeeps.com/forum/phpBB3/vie ... e+inflator

dloc_jeep_KJ · **Posted:** Tue Mar 04, 2008 7:41 pm

ill admit i though the same about airing down for about 2 trips in the KJ (stock) but now i would never run a trail with out airing down(~12-20 MTRs). then again i have a lift and skids and sliders and dont care to abuse them. it really makes a big diff. in ride and in traction. give it a try. i wouldnt in a stock jeep with stock tires but then you probably arent running trails that would call for u to air down anyways. i like rocks so i dont have a choice really so i do. as far as airing back up most of the time i ride with a guy that has on board air and if not ill drive (carefully) to the nearest gas station.

Tokyojoe · **Posted:** Tue Mar 04, 2008 9:43 pm

bugnout wrote:

Rock Lizard wrote:

Airing down on trails will actually prevent a lot of damage to the tire, because the tire can flex over an object, such as a sharp rock or stick/stump. If you take two balloons exactly the same, air one up just enough to be squishy, and the other so it is full and tight, and poke them with a stick, I gaurantee the full balloon will pop first everytime when using the same stick and the same pressure applied to the balloon.

Now that does make sense. So we are protecting the tire by airing down. I can buy that argument.

That's what I said in an earlier post. Guess my opinion isn't worth much....

tommudd · **Posted:** Tue Mar 04, 2008 10:05 pm

Tokyojoe wrote:

bugnout wrote:

Rock Lizard wrote:

Airing down on trails will actually prevent a lot of damage to the tire, because the tire can flex over an object, such as a sharp rock or stick/stump. If you take two balloons exactly the same, air one up just enough to be squishy, and the other so it is full and tight, and poke them with a stick, I gaurantee the full balloon will pop first everytime when using the same stick and the same pressure applied to the balloon.

Now that does make sense. So we are protecting the tire by airing down. I can buy that argument.

That's what I said in an earlier post. Guess my opinion isn't worth much....

its not that your opinion isn't worth much, it's just that they do not value your opinion as much as they should!! :wink:

dieselenthusiast · **Posted:** Tue Mar 04, 2008 10:34 pm

What are some of the best onboard air solutions for Jeeps and other off-road vehicles? According to Troy, this bad boy winch/air compressor combo is a little too heavy for the front of the KJ. :shock:

So give me some healthy "lightweight" and "compact" alternatives. :wink:

Rock Lizard · **Posted:** Tue Mar 04, 2008 11:30 pm

10lb CO2 tank like Ted, Troy and I have. Troy of course has the expensive Powertank (about $400?). Ted and I have more generic ones for about $200.

Airing down, When and why

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