We got snow..should i air down?

Robssoul: don't like to crabwalk?

Dirtridercrf250: you and I are both SOL with those, I stay in the desert with mine.

 

You are right. I've only driven in snow in 9 states, 6 countries, and 3 continents.... including the puget sound where the OP is.

Don't air down, it's useless for where you are driving.

 

Hopefully mine lives out there in the near future. But they just kick out way to easily in the cold.

 

Just edited so no more feelings get hurt. ✌✌✌✌ Also tried to use every color hand so I don't offend but they all came through yellow so I apologize

 

I run slightly lower in the winter. 30 front/28 rear, versus 35 front/32 rear in the summer. The lower pressure definitely helps with traction and I've found the tire less likely to slick over because it flexes more dislodging the packed treads.

 

Better yet - Don’t have to ever air down a halftrack, ever!

 

Dammit, this is making me want to drive in snow.

 

Wow.


Some people don't have a clue on here...lol

 

turn on this, air down that.....just put a good set of winter tires on
and enjoy.

 

I like a person that deals in facts !

 

HMMWVs air down, too. http://www.imfmotorpool.com/058006.PDF

The CUCV, however, does not: http://imfmotorpool.com/053018.PDF


I'm researching this for my own learnings. I'm new to trucks, new to KO2s, new to all the traction controls on the 2017 taco.

My conclusion so far is that manufactures and organizations are largely divided into two camps:

1. Those that have trained, disciplined operators provided with adequate supporting infrastructure
2. All the rest

If you have operators that can adjust the air pressure, and the discipline to obey maximum speed constraints, the tendency is to lower the pressure in snow, mud, and sand.

Civilian authorities only recommend setting to the single recommended pressure. This makes sense, when you realize that their recommendations must work for 16 y/o kids and 86 y/o geezers.

There must be many other inputs to this decision. I suspect that tire requirements predominate all other concerns. Under-inflation can destroy tires, so everything is probably constrained by these pressure limits.

David

 

why do you say that?

 

2” of snow fell in Portland yesterday resulting in 5 wrecks and hour.
101 total.

It’s the only reason I still have cable TV.

 

It's funny that you think the military has trained, disciplined vehicle operators.

 

I am constantly surprised at some of the questions on TW. Everyone wants to know WHAT to do but nobody seems to care WHY.

Like some have already said you air down for floatation and to allow flex in the carcass to absorb the shock from the drivetrain and allow the tire to recover and grip. This is for DEEP snow where your tires risk digging and burying themselves. This is the same theory as off road including soft sand.

On snow covered ROADS if you air down you may decrease the contact patch resulting in LESS traction. On ice this could even be worse. Now we aren’t talking a decrease of 10% such as 30psi to 27. We are talking dropping to 15psi or less.

 

Hence my earlier remark haha.

 

I'm not sure I understand what you mean when you say you can decrease the contact patch by airing down?
My point is snow and ice are a tricky thing to nail down what works the best, really the only way to know when to air down and when to not is experience, I can speak from experience that I have driven on roads that have been plowed here in Northern California and there is a layer of ice on the bottom, in this situation airing down to 15-18 psi is a night and day difference in traction! This may change now that California is salting the roads again. I have also been in slushy snow where airing down is not a good idea or dry powder where there is no benefit to lowering air pressure.
I would say that someone that doesn't have the experience to judge the snow should likely not mess with the air pressure but again IMHO there is no cut and dry answer. I'm not saying I'm right or your wrong just saying different situations require different solutions.
I have been in different situations where both viewpoints were superior.
I have also seen people that are set on one or the other get themselves into trouble as e result.
This is just my opinion in the experience I have had, I have no need or desire to compare who has the most experience just giving an opinion.

 

If an over-inflated tire will wear the center due to bulging and the sides of the thread not contacting MAKING A SMALLER CONTACT PATCH. An under-inflated tire will wear the sides of the tread faster than the center due to a CONVEX curve and the center not making contact (or less pressure at the least). Both conditions will result in a smaller contact patch and less rubber on the road.

Now in the case of very soft materials under your tires like sand or deep snow you need floatation. A hard properly inflated tire will tend to dig whereas an under-inflated or aired down tire will conform better as well as the sidewall flex will absorb some of the shock loads from the drivetrain allowing for the rubber to act as a shock absorber on acceration or deceleration. This helps keep the tires on top of the soft materials.

Now when you run very low pressures on ice or other flat surfaces the tires are convex not giving their full contact patch. Less contact patch = less traction. As you increase the depth of the snow the tire will conform and give more contact patch. On shallow snow covered roads you want the tire to dig to the grippier asphalt below instead of the slick snow of slop on top. Hence the more “normal” tire pressures.

So what do we use on road? In my drive to the store 30 minutes ago I left the lake and went from 1-2” of hard packed snow to 12-18” of drifting from the wind to salted but now drifted over (with ice forming as the snow negated the salt) then wet salted and clear roads. This was all in 1mile. My journey of less than 15 miles round trip had all of this and back and forth. If I aired down it would be dangerous for most of the trip for a small advantage with the drifts.

 

Good points but again, typically the snow where I'm at there is an ice layer underneath, the snow on the top is the best source of traction so I do not want to cut down to the asphalt unless you have studded snow tires.
Is kind of funny as I just had this same conversation with a group of guys from all over the US on a recent trip.
All the California guys say low air pressure and every one els said exactly what you are saying. Maybe us over here are doing it all wrong or maybe there are different solutions for different situations.

 

Listen up, Sergeant - I have an idea.