Snow Wheeling Tire Pressure

[supercarrera]

I'm going snow wheeling on Saturday and I'm wondering what would be the optimum pressure I should run in the snow given I have 275/65/20s? I'm guessing around 15? I'm afraid of going too low and popping a bead. I'm used to 16" wheels and I could air down pretty low when I had 33s on those. But I'm not used to running 20s so I'm not really sure what a good starting point would be given my somewhat limited sidewall.

 

[gaijin]

I'm going snow wheeling on Saturday and I'm wondering what would be the optimum pressure I should run in the snow given I have 275/65/20s? I'm guessing around 15? I'm afraid of going too low and popping a bead. I'm used to 16" wheels and I could air down pretty low when I had 33s on those. But I'm not used to running 20s so I'm not really sure what a good starting point would be given my somewhat limited sidewall.

If one feels the need to air down, my general rule of thumb is to start at 50% reduction in pressure. So, in your case, it depends on which Terra Grappler you are running.

If you have the 275/65R20 116S tires normally running at 30psi, that would mean airing down to 15psi.

If you have the LT275/65R20 tires normally running at 36psi, that would mean airing down to 18psi.

HTH

 

[mark71]

Does airing down really help for snow? I'm seriously curious since I've never tried it.

 

[Markuson]

Does airing down really help for snow? I'm seriously curious since I've never tried it.

Super short version 2-cents:
-If you need to float on top or add spread to grab traction on top: air down.
-If you need to penetrate to solid road just below a slushy surface or cut into a two-tire-track without drifting out of the indent...stay aired up.
——
—Long version 2 cents with photos...
——
Don’t assume airing down is best.
It might be, but...
Some blast-from-my-past photos to consider that there might not be just one solution in snow:

Just my 2 cents here, so grain of salt always in order. OOMV...
-In my snow adventures, conditions can change a lot & you adjust for what you need.

Any time you need to float more than penetrate, or let your tires wrap & use a bigger footprint, airing down is gonna help. Loose sand, mud, pebbles...certain snowy stuff.

But sometimes floating isn’t helpful. If slushy on top, but solid ground just underneath, sometimes you can cut through to a solid surface thats grippy...where floating (airing down) might prevent that. So it depends.

Here’s a example of a time where I didn’t want to float on wet snow bc I could cut through to pretty solid dirt.

This is a shot as I followed my own tire tracks back out. It varied between wet powder and slush on top of pretty solid dirt. See how my tracks cut through to more solid, darker mix of gravel/dirt?

So I didn’t want tread spread here. If it got super thick, and just riding on top, I’d have aired down because the grippy lower stuff might not be reachable.

Sorta similar to S. American muddy, clay-dirt roads, where less float (skinny old-military style tires) was key to cutting through the soupy top-slime and grabbing onto more solid clay that sat an inch or two underneath.

This next shot is thick snow, but super hard packed and nearly perfectly flat from a plow some time before. Traction was a piece of cake but if it had started snowing heavily again, I’d air down. This was about 14 below zero plus wind, btw. Brrr...

Airing down—
Next shot is where I stopped to air down before hitting a portion that looked deep & fluffy (I look buried in this shot, but I’m actually right next to where it was gonna get fluffy)...where no plow had run & airing down made sense again:

Later was on bare pavement for a while and aired back up....but mile or so beyond this next shot I aired down again the fresh snow-drifts across this road got thick and fluffy... not right here, but up ahead on this untouched road:

So...Float...or cut?
IMO no single answer covers “snow wheeling.”

When you want to float...air down.

Last thot—Be prepared in case you REALLY end up stuck. Plenty of fuel, water, warmth in case some goes really wrong and you are broken down, lost or stuck longer. I wheeled alone on those trips. Not so smart...but...

Bad example of being unprepared some girls not doing that:
-A while after leaving this snow-drifted rest stop (photo below) heading toward Wyoming late one night...

...I found two terrified college girls stopped on the mountain highway in their Corolla (no chains)... at about 2 in the morning in hard-blowing snow. They were terrified and almost out of gas!!
Really dumb... but it happens.
-Gave them fuel, and then followed them to the town 90 minutes ahead. Road looked scary but was grippy snow on top of rough-top pavement. So not icy. They were scared to death, but made it fine after about 90 minutes following them in my 100.

Anyway, be smart.
Stuck happens.

To sum up—Floating...or cutting through— both work, but it depends so pay attention and get out & have a look. Getting stuck ain’t fun. OOMV.

M

PS.Oh! And be careful pulling off the frozen highway with an icy curb-like shoulder. It’s surprising how little ice it can take to prevent hopping back up a ledge to pavement. Ask me how I know! (No photos of that spot though..,

 

[Markuson]

PPS. Snowy streets suck...
...but snowy stuff in the boonies?

I love it more than dirt.

Sooo pretty...and the LC makes it a hoot...

 

[CapeTown4x4fun]

Super short version 2-cents:
-If you need to float on top or add spread to grab traction on top: air down.
-If you need to penetrate to solid road just below a slushy surface or cut into a two-tire-track without drifting out of the indent...stay aired up.
——
—Long version 2 cents with photos...
——
Don’t assume airing down is best.
It might be, but...
Some blast-from-my-past photos to consider that there might not be just one solution in snow:

Just my 2 cents here, so grain of salt always in order. OOMV...
-In my snow adventures, conditions can change a lot & you adjust for what you need.

Any time you need to float more than penetrate, or let your tires wrap & use a bigger footprint, airing down is gonna help. Loose sand, mud, pebbles...certain snowy stuff.

But sometimes floating isn’t helpful. If slushy on top, but solid ground just underneath, sometimes you can cut through to a solid surface thats grippy...where floating (airing down) might prevent that. So it depends.

Here’s a example of a time where I didn’t want to float on wet snow bc I could cut through to pretty solid dirt.

This is a shot as I followed my own tire tracks back out. It varied between wet powder and slush on top of pretty solid dirt. See how my tracks cut through to more solid, darker mix of gravel/dirt?
View attachment 1900641
So I didn’t want tread spread here. If it got super thick, and just riding on top, I’d have aired down because the grippy lower stuff might not be reachable.

Sorta similar to S. American muddy, clay-dirt roads, where less float (skinny old-military style tires) was key to cutting through the soupy top-slime and grabbing onto more solid clay that sat an inch or two underneath.

This next shot is thick snow, but super hard packed and nearly perfectly flat from a plow some time before. Traction was a piece of cake but if it had started snowing heavily again, I’d air down. This was about 14 below zero plus wind, btw. Brrr...
View attachment 1900640

Airing down—
Next shot is where I stopped to air down before hitting a portion that looked deep & fluffy (I look buried in this shot, but I’m actually right next to where it was gonna get fluffy)...where no plow had run & airing down made sense again:
View attachment 1900642

Later was on bare pavement for a while and aired back up....but mile or so beyond this next shot I aired down again the fresh snow-drifts across this road got thick and fluffy... not right here, but up ahead on this untouched road:
View attachment 1900644

So...Float...or cut?
IMO no single answer covers “snow wheeling.”

When you want to float...air down.

Last thot—Be prepared in case you REALLY end up stuck. Plenty of fuel, water, warmth in case some goes really wrong and you are broken down, lost or stuck longer. I wheeled alone on those trips. Not so smart...but...

Bad example of being unprepared some girls not doing that:
-A while after leaving this snow-drifted rest stop (photo below) heading toward Wyoming late one night...
View attachment 1900645
...I found two terrified college girls stopped on the mountain highway in their Corolla (no chains)... at about 2 in the morning in hard-blowing snow. They were terrified and almost out of gas!!
Really dumb... but it happens.
-Gave them fuel, and then followed them to the town 90 minutes ahead. Road looked scary but was grippy snow on top of rough-top pavement. So not icy. They were scared to death, but made it fine after about 90 minutes following them in my 100.

Anyway, be smart.
Stuck happens.

To sum up—Floating...or cutting through— both work, but it depends so pay attention and get out & have a look. Getting stuck ain’t fun. OOMV.

M

PS.Oh! And be careful pulling off the frozen highway with an icy curb-like shoulder. It’s surprising how little ice it can take to prevent hopping back up a ledge to pavement. Ask me how I know! (No photos of that spot though..,

Thanks for the very well put together description

 

[skrypj]

In my experience, if the snow is super deep to where you are dragging axles through it, the lower you go, the better. Since you probably are not putting a ton of stress on the tires in the deep snow, debeading should not be a huge issue. I see two reasons for this:

1. The lower pressure gives you more surface area and hopefully you float better and keep your axle and belly out of the snow.
2. It spreads the tractive forces over more snow. Say you have 20 tread blocks engaging with the snow at 8 psi, but you drop to 5 psi and now have 30 tread blocks engaging. Since the snow is likely to give way since its not solid, having the forces spread out over more snow means it will hold better before you start spinning.

I had a 1995 SAS'd 4Runner on 37's and at one point was running them down at 5 psi on a regular old set of 4Runner TRD Offroad wheels. The difference from going from 12 psi to 8 psi is very noticeable, and going from 8 psi to 5 psi was very noticeable. I was getting stuck at 8 psi but then it would pull through at 5 psi.

The guys who build snow wheeling specific rigs with 40" mud tires and beadlocks will run 2-3 psi I believe.