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How low can you go when it comes to airing down??

G

gone postal

NAXJA Forum User
Location
St. Augustine, FL
Okay, general question here.

I have all-terrain tires on my XJ - size 235/75/15. Max PSI says 44 - I usually run in the 33-35 range when cold.

So, how low can I go when I air down, but still be road worthy for a short while while driving home (let's say 5 miles)? 25? 20?
 
i normally take my ATs down to 20 psi and drive them on the road until i find a gas station to refill them up
 
You don't want to run aired down on the road any longer than you have too. With the tires aired down it makes the sidewall flex alot more and if you go around a sharp curve there's a possibility of popping a bead. Most people who air down on the trail either have a compressor or other air system with them to air back up or stop at the first gas station they come to so they can air back up.
 
It really depends. I normally run 35x12.50's at about 25 psi. Could I run them at higher PSI and get better mileage? Sure, but I also wear out the tires MUCH faster that way in the terms of cupping and uneven wear. At 25 psi, the tread wears flat and even which is more important to me than gas mileage.

But back to your question, I wouldn't go much lower than 18-20 psi or you do risk the chance of getting into an accident because of the lack of control at speed and sloppy handling.
 
gone postal said:
So, how low can I go when I air down, but still be road worthy for a short while while driving home (let's say 5 miles)? 25? 20?
Click to expand...

I would not be concerned driving 5 miles on pavement at 15psi. Be careful and realize you are not in a sports car. Keep your speed down and you will be ok. Not a big deal.
 
Driving 5 miles on pavement aired down.
15PSI is OK, Just take it VERY EASY!!!
Don't go faster than 30 Mph or so & No Abrupt changes in direction.
 
At hot springs I would run into town on 10-12#, road a lot better that way too. Just dont take corners too fast. If you are worried I would keep them around 12-15.
 
I have 35 Krawlers and ran 12 in the rear and 15 in the front. I drove all over hell that way in Moab, and it handled better than aired up. My dad has 37 Krawler mounted on Walker Evans. He can't air up more than 20 PSI ever, and drives it all over town with no problems. He aired down to 9 PSI front and rear with no problems. It really has to do do with what your tires are rated. The truck tires run better with less air than the small suv, truck tires.

We air down and disconnected for the week, and don't air back up until we go home.
 
With a 235/75 on a resonably loaded XJ I feel 20 to25psi is about right. That small a tire is going to need a little more air than a 33" or 35" high flotation tire that can run in the 8 to 15psi range. Just be sure to take it easy on the road while aired down!
 
Folks regularly run trail pressure, 10-15 lbs, for the drive back to where ever. Could be back to camp, back to town, back to a gas station, whatever. When we go to Moab, we air down the first trail day, run all week, and air back up when we go home. That's driving to and from all the trails and around town to shop and eat. Just remember that you have low pressure and drive accordingly.

Also, a larger tire can handle less pressure than a smaller tire, so that should be taken into account. It's the volume of air in the tire that carries the load, so a 235/75 might take 20 lbs while a 35x12.50 would be the same at 12 lbs.
 
Goatman said:
Also, a larger tire can handle less pressure than a smaller tire, so that should be taken into account. It's the volume of air in the tire that carries the load, so a 235/75 might take 20 lbs while a 35x12.50 would be the same at 12 lbs.
Click to expand...

x2
 
The Hard Struggler said:
With a 235/75 on a resonably loaded XJ I feel 20 to25psi is about right. That small a tire is going to need a little more air than a 33" or 35" high flotation tire that can run in the 8 to 15psi range. Just be sure to take it easy on the road while aired down!
Click to expand...

Yeah, this is what I was getting at with the question. I know that my small tire can't air down as low as a 35 and still hold a bead.

There are plenty of gas stations on the way home, but I have a compressor at home so I was just looking to save the hassle of stopping, $.50, etc.

Living in FL, there isn't a lot of spots to wheel, but i want to just do some basic experimenting the next time i'm at teh beach and see just how big of a difference airing down can make. I'll give 15-20psi a shot and stop at the gas station that's 1/2 mile from the beach ramp to air back up.

Thanks for the insight!!
 
I usually run my 31x10.50 @ 13# on the trail and then go to my hotel or the store usually about 10-20 miles away from where i wheel and have not had any problems.

Therefore i would say if you would not feel safe wheeling @ that low of pressure with possibility of popping a bead then, run at 15-18# and try it out. you may want more you may want less. I have had much luck at 15-18# but i love the traction i have in the rocks when i am down to 13#.

Maybe a suggestion but i like to learn from my mistakes so maybe see how low you can go and feel safe on the road and always wheel or be with someone who can help you seat your bead again and don't go that low again.

Josh
 
If you want to be able to drive 5 miles or so stay at around 12-15 lbs. If you want to go any where on the beach try a lot lower. Around 8 lbs will let you idle along through the softest sand. That would be on a stockish size tire. Keep letting the pressure down and see the difference in flotation. This is for at the beach or dunes only. On my beater YJ with 33 BFG MTs i run about 6lbs and to climb the Sliver Lake sand dunes at a crawl I will drop down to 3.5 or 4 lbs. It takes lots of nerve to go that low but the flotation is unbeliveable. Have fun at the beach.
Ron
 
In snow i run 8 lbs, in the summer on rocks 10-13. 33x12.5 trxus mts, I have oba though so if i go on pavement i air back up and run about 25-30lbs

I also just put beadlocks on so in the snow ill be able to run 3-8 lbs much more safely... Before i had on board air i drove 10-15 miles on 10-12 lbs, No problems...
 
In the XJ we run 12-14# in the 31-10.50's... in my Ramcharger with 35-12.50 Mud Rovers, I run 10-12#... sand, mud or snow... then usually drive 5-6 miles to nearest air... have been doing this for years with no ill effects... just use common sense as far as driving to and from to air back up... slow and easy wins the race!
 
All of the above assumes that the tires are properly matched to the rim width. Nobody has mentioned rim width yet, so I thought I would. :wave:


With that said, I take my 33x12.50's on 8" rims down to 12psi and have never had a problem. Not a one.
 
I ran my 235/75/15 BFG ats at 12 on the freeway for about 10 miles after the first time I went wheeling. it was ok kept the speed around 50. After that I bought a compressor.
 
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