How long have you run your tires on street with low PSI

[joseluis.17g]

Hi!
First of all I´m sorry about my spelling and grammar, english isn´t my first language
with that out of the way...
Most of my overlanding trips have a mix of tarmac and dirt, and I´m wondering if I should air up for the tarmac bits in between
I´ll give you some context, I drive a 2016 VW amarok which weigths around 5800lb (it´s got steel front and back bumpers, winch and all my camping gear) I´m running 255/85r16 whichs is a 33x10 Yokohama Geolander MT003 LT
most of the trails I run at 25-20PSI and the streets bits at most are 15-20 miles but almost exclusively highway (60-70mph)
My question is should I be airing up and then down again, or can I run 25-20psi on the street and not worry about ir
I do have a power tank and my tires being so norrow it never takes me more than a few minutes, but it seems a bit excecive doing it for every strech of tarmac

let me know what you guys think!

 

[kunstmilch]

It is a matter of speed. If you are going 10 miles but wat to drive at 60 then air up, if you are ok going 40 then not necessarily the worst. It depends on if its a safe stretch of road to go slow on but its not worth causing an accident over minor convenience.

 

[Ubiety]

For a short/slow bit of tarmac I would not worry about it; for the distances/speeds that you describe I would definitely air up. Running low for long distances at speed is going to cause your tires to heat up and that will decrease their life time.

 

[old_man]

My standard everyday pressure is 28psi. I have forgotten to air up and run 14psi for months with no adverse issues other than a smooth ride and a bit mushy steering. My tires are 35x12.5x15s.

 

[YoKramer]

So long as you always keep an eye on your tires for sidewall damage and de-laminating tread you should be fine not airing up on those stretches. Ive run 10-15psi on the way home from rock crawling at 50-60mph on a 45min drive and then to work to air them up the next day another 30mins quite often without issues. Your sidewalls will take a bit of extra wear and heat from it but again if you are inspecting your tires regularly you should be fine. I run the Falken Wild Peak 33x11.5 M/Ts the higher load range and thicker sidewalls help a lot with surviving the lower pressures on road as well as off.

 

[Mustang03]

The longest we've run is 30 miles at 20 psi on our Ram 3500 which normally runs at 70 psi. (The air pump malfunctioned.) We babied it along at 35 mph max on a very hot day and had no problems afterwards. We did, however, buy a new air pump!

 

[grubworm]

a lot of times im just too lazy to air up after getting a nail in my tire and they seem to do OK with low pressure

 

[Ubiety]

This lazy solution has allowed me to keep sufficient pressure in my tires more times than I want to admit.

 

[Sylvester]

I run around 36psi on my 40"s Except when I'm out and about wheeling Then I leave them at 10psi Have driven 140 Miles at 65 to 70 at 10psi I'm sure it will wear Faster but there is no Safety Concern's That I can tell

 

[Longshot270]

You can also ask the question another way, do you need to air down that low for the dirt?

 

[Ubiety]

You can also ask the question another way, do you need to air down that low for the dirt?

That is a very subjective question fraught with opinion and personal choice and of course terrain/conditions ;) For me airing down is a comfort thing, not only for myself but mainly for my wife. If I can keep her happy then I have a better chance of her coming along, driving my truck, and scaring me the next time. Hahaha

 

[old_man]

You can also ask the question another way, do you need to air down that low for the dirt?

Airing down really helps on washboard roads and to cushion the harshness of the trail. On trails with tons of big rocks, it helps traction. If traction is required that much, you better be in a group and have a winch and recovery equipment. Airing too far down without really being required has lead to lots of ruined tires and busted rims, not to mention popping beads and having to reseat them or change your spare.

 

[MOAK]

On the road I keep 38lbs. I air down to 24 for trails, no matter how hard core. In between trails I’ll air up to 32lbs. Once we head home, 2,000 miles plus, and are done in the dirt I’ll pump em back up to 38psi. Too low pressure at high speeds will overheat the tires and lead to premature failure, so I take the time to air down & up. Anal retentive? Sure, but I always get more than 50,000 miles out of a set of 285/75/16s. Here’s my current set with 42,000 miles on them.

 

[Sylvester]

Technically You don't need to air down at all, It is just for comfort mostly Unless your in Sand

 

[Ubiety]

On the road I keep 38lbs. I air down to 24 for trails, no matter how hard core. In between trails I’ll air up to 32lbs. Once we head home, 2,000 miles plus, and are done in the dirt I’ll pump em back up to 38psi. Too low pressure at high speeds will overheat the tires and lead to premature failure, so I take the time to air down & up. Anal retentive?

That is just about my regimen; pressures may vary slightly. Anal retentive? Heck yeah but tires are expensive and I'd rather not spend my hard earned shekels on things that could be avoided.

 

[Ubiety]

Technically You don't need to air down at all, It is just for comfort mostly Unless your in Sand

Helps a lot to air down in snow as well.

 

[old_man]

I want to interject, the tire pressure listed on the tire is NOT the pressure you want to run. That is the absolute pressure to every be allowed.

If you air up to the MAX pressure then go out and run in the heat at highway speeds, the tire will heat up and the pressure will increase, possibly leading to a blowout.

The pressure you want to run is somewhere below the MAX pressure. I don't have time to go over determining that pressure in detail at the moment, but there is a common test called the chalk test or contact patch test. You coat the tread of the tire with chalk and drive a short distance. You then look at where the chalk is still on the tire.

The goal is to get good and even mating of the full width of the tire to the road. If you air up too much, you will wear out the center of the tire as well as have a vehicle that it very skittish and wants to oversteer.

If you under inflate the tire, you will wear off the edges of the tire prematurely and you will have understeer.

You have to find the sweet spot, and that pressure depends on the width of the tire, the width of the rim, the height of the sidewalls, the stiffness of the sidewalls and the load, and type of driving (curvy or straight). The shocks you have can even play into the equation over a long period. That is why you do a chalk test with your set of conditions.

My rig, running 35" tires BFG AT LO's works best with 26-28 psi. I am still experimenting with the new MT tires. They seem to be a lot more touchy.

 

[tjZ06]

It's all about heat. Lower pressures cause the sidewalls to flex (obviously, since that's why we lower air pressure, to lengthen the footprint and provide a better ride because of the sidewall flex) which generates heat. At slow speeds on the trail it's not an issue. At higher speeds, it *could* be.

There is no exact right answer as to what is safe (like 55 MPH for 30 minutes at 25psi or something like that) because every vehicle and tire combo will be different. For example, my truck w/ FWC is just over 10k lbs and I run 65psi cold (max for my tires) for street/freeway driving. When I "air down" it's typically only to 30-35psi, which is as high (or higher) than most people's street setting. However, at 30ish PSI I'm getting as much sidewall deflection in my 37x13.5-17"s as say a stock JLUR on factory tires would get at maybe 18psi with one of the factory tire fitments.

The reality is the *best* way to know what is safe is by monitoring heat. You can buy aftermarket TPMS setups that also give heat readouts. You can monitor tire heat at street PSI to get an idea what "normal" looks like, then when you have to drive pavement aired down you can watch to make sure you don't exceed that by "too much" (but then, what is "too much"?). A cheaper way to do this would be with a little infrared heat gun, but obv that would require stopping to check. Finally, tire pressure is a loose analog for tire heat, but this will change depending on what your tires are filled with ("regular" air, co2 from a Powertank, nitrogen, etc.).

All of that said, I pretty regularly connect trail sections with pavement and don't air back up. I have an ARB twin compressor on my truck but even with that it takes about 30min to air up from 35psi to 65psi. I do have a Powertank setup (well, 2 in fact) but I already bring soooooooooooo much stuff I've stopped taking it. It'd just be way too much to air up/down for every pavement stretch. I try to avoid freeways aired down, and if I have to do it I stick to 55-60 MPH for short stretches and stop often. If I had to do more than say 10-15 miles on a Freeway I'd air back up, but that's really not based on data/science just a gut feeling I guess...

-TJ

 

[Ubiety]

A cheaper way to do this would be with a little infrared heat gun

I carry one of these in my center console and check tires and rim centers (bearings) at gas and rest stops during long road trips.

 

[old_man]

I carry a hammer to check the tire pressure and use my hand to sense the heat. Old School