lowest PSI on road?

[Andrew Bynum]

Depends on speed more than anything

For a long trip, sure, it’ll build heat eventually.

Cornering speed and pavement temperature would be my top concerns in most use cases.

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[Scott R Nelson]

I drop my tire pressure to 20 psi as soon as I get to the dirt. It rides much smoother over small rocks and washboard sections than when aired up all the way to 39. I'll drive a few miles on pavement at that pressure, but not too far and not too fast.

Just yesterday I was considering driving 28 miles from one dirt section to another and decided that I probably didn't want to drive that far on a 55 mph road at the lower pressure. Instead, I aired back up and didn't bother going to the other section. I watch the tire pressure closely if I'm aired down and on pavement. If it goes up more than about 2 psi it means I'm generating a bit more heat than I would like.

Unless I'm in some deep very dry sand, I don't see the point in going below 20 psi. You get much below 15 and you run the risk of popping a bead and an instant flat tire.

Random photo of my Bronco out in the wild - just because:

 

[lakesinai]

hi, every time I’ve been off-road I have not lowered the tire pressure on my bronco because I’m scared of ruining the tires when I’m back on road, since I have no compressor (getting the american advanture labs one soon) so there is no point in getting a portable one right now.
tomorrow morning im doing some moderate offroading and want to lower the tire pressure, but i will have to drive an hr back to the nearest pump (costco)
whats the lowest i can do for onroad driving?

Back before people had fancy pumps, in the 1950's and 1960's, these type of simple air tanks were very popular for trips to the beach. Assuming you air down to 15-20#, a tank might let you add 10# per tire, or more depending on tire size, to allow safer highway travel for the trip home. Since you plan to install an inflation pump, this $38 tank is only 16x12x9 inches for 5 gallons of air, and a cheap solution for the interim. You'll have to do the calculations, there's an 11 gallon version for $70, but that takes up more space 14x23x13. These work well, if you fill them! My installed ARB pump cost $750 so those aren't cheap. A good portable pump is a good value as well. But there's an elegance to a simple tank with a 3' hose to get you home!
https://www.harborfreight.com/5-gal...7cEpesU6923A_7Q-5H0jup11fZmazGVhoCjXoQAvD_BwE

 

[swami37]

You don’t need to air down

 

[Scott R Nelson]

Since you plan to install an inflation pump, this $38 tank is only 16x12x9 inches for 5 gallons of air, and a cheap solution for the interim. You'll have to do the calculations, there's an 11 gallon version for $70, but that takes up more space 14x23x13. These work well, if you fill them! My installed ARB pump cost $750 so those aren't cheap.

The serious Jeep guys that I've met carry a nitrogen bottle at over 1000 psi that is both small and fills up a tire pretty quickly.

My Smittybilt portable air pump was around $150. You don't need to spend $750 for a decent air pump. Mine fills all four Sasquatch tires in 10 minutes and takes up less space than this thing you're proposing.

 

[Rydfree]

You don’t need to air down

I generally air down anytime I will be off pavement for any length of time simply for the better ride. The wife doesn't get bounced around as much and her back appreciates it. I have a Moreflate 10six pro that I take on serious trips but for most rides I throw in the the little Ryobi inflator. Takes about 3 minutes per tire but the cordless inflators are convenient and I use it a lot around the property. Airing up mower tires, the golf cart, bicycles and keeping the motorcycle tires at correct psi makes the small cordless air compressor well worth the $$.

RYOBI ONE+ 18V Cordless High Pressure Inflator (Tool Only) PCL001B - The Home Depot

 

[ghazi223]

I generally air down anytime I will be off pavement for any length of time simply for the better ride. The wife doesn't get bounced around as much and her back appreciates it. I have a Moreflate 10six pro that I take on serious trips but for most rides I throw in the the little Ryobi inflator. Takes about 3 minutes per tire but the cordless inflators are convenient and I use it a lot around the property. Airing up mower tires, the golf cart, bicycles and keeping the motorcycle tires at correct psi makes the small cordless air compressor well worth the $$.

RYOBI ONE+ 18V Cordless High Pressure Inflator (Tool Only) PCL001B - The Home Depot

woah that little thing is enough for 4 tires?
from around 15-20 psi to 35+?

 

[Rydfree]

woah that little thing is enough for 4 tires?
from around 15-20 psi to 35+?

It has worked well for my 33" KO2s but I only air down to 25/28 and then just go back to 35psi for the trip home

 

[FilmcoBronci]

im going into soft sand, not just fire roads

We spend quite a bit of time in soft sand. You will want to invest in a compressor for sure and be at least in the 20's PSI. We work at sandy sites. Lighter drier western sand (Top ) we run at 20-23. Denser wetter mid western sand roads we run at 26-29.
Get a compressor though. That makes all of these conversations less stressful.

Side note: We always air back up to OEM 39Lbs (Cold) and are probably going to get close to 70k Miles on our Falken Wildpeak AT3_W C rated. Love them and are amazed at their versatility in Sand, Wet and Dry Snow and moderate Rocky Mountain Roads. Generally run short stints on rutted sandy and sloppy roads at full 39 Pounds.

 

[lakesinai]

The serious Jeep guys that I've met carry a nitrogen bottle at over 1000 psi that is both small and fills up a tire pretty quickly.

My Smittybilt portable air pump was around $150. You don't need to spend $750 for a decent air pump. Mine fills all four Sasquatch tires in 10 minutes and takes up less space than this thing you're proposing.

"Need?" Now that's an interesting word to use by one person to another when discussing outfitting off-road vehicles! The OP was looking for a short-term solution about airing down until he installed his air pump. We've provided that. We all make choices based on personal use and monetary value. I thought my portable air pump was just fine for decades until I decided it was time for an installed system. Well worth it, to me. Much more convenient, quicker. I have 33" tires. If I had 35's, I'd buy the ARB twin.
KR-Engine bay bracket: $250
ARB-Single pump: $360
ARB hose kit $100 & Inflator $70
Install: $200

 

[OuterBanks]

I wouldn’t be doing ANY off roading without myself or someone having basic recovery equipment, to include communications. Driving off or on road, there are always risk, but I ain’t going to be stuck in the middle of nowhere without such things. Maybe it’s cause I’m older, a bit wiser, and “been there, done that” kind of thing.
If you are muddling where it’s half of your tire, don’t listen to your passenger who says “turn, turn, turn”. Needless to say, a track recovery vehicle had to pull us out..This was back in 98’ Bosnia.

To each their own.

 

[Brian_B]

woah that little thing is enough for 4 tires?
from around 15-20 psi to 35+?

I have one of these - it will do four 35” from 15 to 25 in about an hour.

The Milwaukee will do the same in about 4 minutes

 

[Canyon Coolers]

hi, every time I’ve been off-road I have not lowered the tire pressure on my bronco because I’m scared of ruining the tires when I’m back on road, since I have no compressor (getting the american advanture labs one soon) so there is no point in getting a portable one right now.
tomorrow morning im doing some moderate offroading and want to lower the tire pressure, but i will have to drive an hr back to the nearest pump (costco)
whats the lowest i can do for onroad driving?

I've done 20 psi (17 or 18 psi cold) over long distances on both stock and aftermarket tires. Handling is of course spongy but otherwise it was fine. Keep in mind hard cornering is riskier then straight line speed and you will be ok.

 

[CV428]

There is no all-encompassing minimal tire psi- it depends on the tire, size, load, speed, duration, and ambient temperatures.

If your tire pressure is dangerously low, the tire will heat up and stink. The more the tire flexes, the more internal/rolling friction it goes through and if it can't shed that heat, it builds up and eventually leads to failure. If you have ever gotten a sudden flat tire on the highway, pulled over, and felt the tire- sometimes it's hot enough to scald you.

17 years ago I drove from NH to CT on 8-10psi on Mickey Thompson ET Streets (315/35r17 if I recall...). Not a ton of sidewall, it was fine, but it was also late October in New England. I left the drag strip later than expected and the first gas station I stopped at didn't have a working air compressor, so I just drove home at ~55mph. I wouldn't go that low on a truck tire. Maybe 18-20psi short term...

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