Lowest pressure for non beadlock Wheels

[Johnnyb]

So I'm running 17 inch non beadlock aluminum rims, I was wondering what the lowest pressure I can safely run in my tires is for cinders and sand?

THX,
JB

 

[Broncobowsher]

Too many variables.
17" has nearly no impact
Tire width and wheel width are the bit ones. Diameter also plays in. For 17" I will just assume radial at this point.
Cinders and sand can go lower than the rocks most of the time. Rocks tend to put the weight on the sidewall, pretty much worst case. As long as you are just going up/down and not loading the sidewalls, minimal risk of pushing one off sideways.

Best I can guess, low teens.

 

[Johnnyb]

Wheel is 17X9 and tires are BFG A/T 35X12.5.
I was thinking 12-16 PSI, depending on how soft the surface?

THX,
JB

 

[Broncobowsher]

That's the right ballpark.
How you are driving it also play in. Just out for a cruise, or testing how much HP is under the hood.

 

[Johnnyb]

Little bit of both. Do some pretty good hill climbing out at the cinders.

 

[nvrstuk]

Rim brand and tire brand are huge variables.

You can have same size rim and tire right next to each other and they will act totally different. We've been thru this several times in soft snow which is much more forgiving than sand.

Just don't go FAST or turn the steering wheel sharply or you might find out how fast the tire goes flat.

 

[DirtDonk]

We've been thru this several times in soft snow which is much more forgiving than sand.

Yeah, except that the water acts as a lubricant for the bead to use to peel itself right off the wheel!
The cold is good, the fact that the "water" is solid most of the time is good. But eventually it turns into water again, and starts it's lubrication duties.

Paul

 

[Johnnyb]

Thanks for the advise @nvrstuk @DirtDonk.
I would prefer not, but if I loose a bead, i have compressor, spare & tools.
Plan on keeping it on the higher end of aired-down in most situations!

-JB

 

[stout22]

I have run down to around 12 psi in the rocks w/o an issue but maybe I was lucky. I now have beadlocks.

 

[nvrstuk]

Yeah, except that the water acts as a lubricant for the bead to use to peel itself right off the wheel!
The cold is good, the fact that the "water" is solid most of the time is good. But eventually it turns into water again, and starts it's lubrication duties.

Paul

Yeah, but until you lose a bead there's no water there yet to act as the lubricant, because if there is you've already lost air!

We used to run 10psi in snow. I have a video buried in my phone with my daughter & I doing 60 mph with waaaay too low air pressure (pre bead lock days) across deep snow.

 

[Broncobowsher]

Thanks for the advise @nvrstuk @DirtDonk.
I would prefer not, but if I loose a bead, i have compressor, spare & tools.
Plan on keeping it on the higher end of aired-down in most situations!

-JB

Can of starting fluid and something to light it with as well.
Very few mobile compressors have enough volume to start seating a bead like shop air does.

 

[gnpenning]

Check out rim locks. You can make a cheap homemade version. While not great it's better than what you have.

 

[Apogee]

Without beadlocks, I always ran 10-12 PSI in my truck, trailer, etc, whatever was going out in the dunes. Anything higher and I tended to dig-in and get stuck, and anything lower and I'd run the risk of losing a bead, or getting enough sand in the bead, that it would need to be dismounted anyway to be cleaned so that it could hold air again. My friends and acquaintances who thought 4-8 PSI was a good idea tended to spend more time working on tires than driving 'em.

 

[Tricky Dick]

As others said, too many variables. I've run as low as 8 psi on one set comfortably, had a different wheel/tire combo that anything below 20 was asking for trouble. Outside of that particular set I've never had anything that wouldn't do at least 12.

 

[Yeller]

@Tricky Dick and @nvrstuk nailed it. Go try it and see. I’ve had some I could run at 2psi and never have an issue and I’ve had some that 20 where issues began.

 

[Nothing Special]

I run 11 psi and haven't had any trouble.

As for my variables, that's with 33/12.50-15 ProComp Xtreme MT on steel wheels. Mostly rock crawling, but I did play in the sane at Sand Hollow on one trip. I have a stockish 302 and about a 70:1 crawl ratio. I drive like I don't want to break anything, but I still do some pretty hard trails and obstacles

 

[chrlsful]

BFG AT KO? 5 - 12 or 16 -20 ?

on bead lock or rim lock a plate runs round rim on inside of tire & that outside thing we see see has thru bolt to it?
Outside plate, rim/tire, inside plate sandwich, above tire - ie no holes in tire?

Those can go down to 2, 3 lbs psi?
All psi lowering assumes low MPH ? How low? (I no depends on surface)
What isa ‘cinders’ condition. Dont believe we have that back east (running a dry river corse?)

 

[Johnnyb]

BFG AT KO? 5 - 12 or 16 -20 ?

on bead lock or rim lock a plate runs round rim on inside of tire & that outside thing we see see has thru bolt to it?
Outside plate, rim/tire, inside plate sandwich, above tire - ie no holes in tire?

Those can go down to 2, 3 lbs psi?
All psi lowering assumes low MPH ? How low? (I no depends on surface)
What isa ‘cinders’ condition. Dont believe we have that back east (running a dry river corse?)

Volcanic cinders. They're like tiny sharp pea gravel on down to talcum powder. They're also pretty light so they like to get out of the way of tires trying to push on them, unlike traditional beach sand or dune sand.
Climbing a cinder cone can present 30 40 50% grades and quite a challenge.

 

[chrlsful]

a beed lock is same as rim lock? Is 4 plates? 2 on each rim (of 1 tire), inside’n outside?
Squishing rim & tire between these plates? No nuts. Inner plate has threads to catch the bolt driven from outside?

Up here we winter race on ice w/nails thru tire. "Bead lock" is new to me...

 

[Dave]

A little nostalgia. My dad was kind of a pioneer of running in our local sand dunes back in the 50s. He built a machine to split rims, roll spacers, and weld em. Made a zillion when the VW scooters caught on. We ran about 5 psi with tubes until implement tires became available. They used a tire inflator that screwed into a spark plug hole. It had a check valve that let air in and on the intake and power stroke. And pumped on the compression stroke. Had to pump up for the flat tow home.







The Hamlin Lake dunes was a great playground to grow up with in your back yard. We road dune scooters and snowmobiles there for years. Finally got closed down when purchased by the State Park when it got inundated by VW dune scooters. Too many and too much trash including pull tabs and broken bottles. Many used for target practice.

Pretty much a wilderness area now with very little foot traffic.

We did have about 10 acres of sand hills on the old farm. Some pretty nice hills. When the farm got sold it was mined off.

Keep telling my brother we grew up in the best of times. Private, state, and federal land was wide open for our dune scooters, snowmobiles, and dirt bikes.

Silver Lake, about 30 miles south, is still open but pretty tightly controlled.