Topic: Why Air Down Your Tires Off Road

[300k]

:031

/thread

that isn't a legitimate timestamp, and this isn't reddit.


As far as the video, look at the terrain he's on. boulders. Look at the terrain I'm on. large, flat rocks. nothing for the tire to wrap around on. tons of off camber stuff where tire structure is important.

[blackdiamond [OP]]

that isn't a legitimate timestamp, and this isn't reddit.


As far as the video, look at the terrain he's on. boulders. Look at the terrain I'm on. large, flat rocks. nothing for the tire to wrap around on. tons of off camber stuff where tire structure is important.

If I were "Bill Gates" I'd purchase a shackle load cell and fly down to your place for a little testing.  We'd tie your back bumper to an anchor with the shackle load cell in the connection and then measure the maximum load you could put on it before churning your tires.  First with them at street pressure and then with them aired down.  It would just need to be a flat consistent surface.  Just for giggles we'd check all of the following configurations just to see what the results were:

(1) 35 psi 2wd low low range (hubs unlocked) rear diff open
(2) 35 psi 2wd low low range (hubs unlocked) rear diff locked
(3) 35 psi 4wd low low range (hubs engaged) differentials open
(4) 35 psi 4wd low low range (hubs engaged) differentials locked

(5) 10 psi 2wd low low range (hubs unlocked) rear diff open
(6) 10 psi 2wd low low range (hubs unlocked) rear diff locked
(7) 10 psi 4wd low low range (hubs engaged) differentials open
(8) 10 psi 4wd low low range (hubs engaged) differentials locked

We might find that 4wd, especially, aired down would put far too much stress on things to be worth the fun...

[H8PVMNT]

300K I have your best interests at heart, stop flicking poo back and forth with these guys and start up that research thread I was talking about.  Prove things wrong, prove things right, make it silly and fun.  It will all be good.   

https://www.youtube.com/watch?v=x5HaLo95ufw

[300k]

If I were "Bill Gates" I'd purchase a shackle load cell and fly down to your place for a little testing.  We'd tie your back bumper to an anchor with the shackle load cell in the connection and then measure the maximum load you could put on it before churning your tires.  First with them at street pressure and then with them aired down.  It would just need to be a flat consistent surface.  Just for giggles we'd check all of the following configurations just to see what the results were:

(1) 35 psi 2wd low low range (hubs unlocked) rear diff open
(2) 35 psi 2wd low low range (hubs unlocked) rear diff locked
(3) 35 psi 4wd low low range (hubs engaged) differentials open
(4) 35 psi 4wd low low range (hubs engaged) differentials locked

(5) 10 psi 2wd low low range (hubs unlocked) rear diff open
(6) 10 psi 2wd low low range (hubs unlocked) rear diff locked
(7) 10 psi 4wd low low range (hubs engaged) differentials open
(8) 10 psi 4wd low low range (hubs engaged) differentials locked

We might find that 4wd, especially, aired down would put far too much stress on things to be worth the fun...

stupid test. you should test something along the lines of this, which is what I'm talking about. if the tire isn't wrapped around the rocks,and you just have your side lugs on a rock, you're putting say 1,000 lbs through a contact patch of 2 sq inches. it may not be as much "mechanical" grip as the tire being wrapped around the rock, but it will be enough grip to get you over the rock and thru the trail without airing down for 20 minutes and airing up for 40.

[Lewis Hein]

300K I have your best interests at heart, stop flicking poo back and forth with these guys and start up that research thread I was talking about.  Prove things wrong, prove things right, make it silly and fun.  It will all be good.   

https://www.youtube.com/watch?v=x5HaLo95ufw

Emperical evidence rules!!

[Rockcrawlintoy]

stupid test. you should test something along the lines of this, which is what I'm talking about. if the tire isn't wrapped around the rocks,and you just have your side lugs on a rock, you're putting say 1,000 lbs through a contact patch of 2 sq inches. it may not be as much "mechanical" grip as the tire being wrapped around the rock, but it will be enough grip to get you over the rock and thru the trail without airing down for 20 minutes and airing up for 40.

Maybe for one rock on flat ground. Add many rocks with silty dirt trying to climb both front driver side tire and rear passenger, oh yeah going up hill. Who takes 20 minutes to air down and 40 to air up?

[Snowtoy]

stupid test. you should test something along the lines of this, which is what I'm talking about. if the tire isn't wrapped around the rocks,and you just have your side lugs on a rock, you're putting say 1,000 lbs through a contact patch of 2 sq inches. it may not be as much "mechanical" grip as the tire being wrapped around the rock, but it will be enough grip to get you over the rock and thru the trail without airing down for 20 minutes and airing up for 40.

So you are wiling  to incur the jarring ride to get to the trail, a ride that abuses both you and your rig, just to not have an issue with the occasional side hill and loss of traction?  You do realize that w/an OBA system, you can add psi when needed, allowing you to tailor your tires to the terrain they are on at the time.

If you don't have the time to spare to air up/down, how are you ever going to deal with a breakage?

[300k]

So you are wiling  to incur the jarring ride to get to the trail, a ride that abuses both you and your rig, just to not have an issue with the occasional side hill and loss of traction?  You do realize that w/an OBA system, you can add psi when needed, allowing you to tailor your tires to the terrain they are on at the time.

If you don't have the time to spare to air up/down, how are you ever going to deal with a breakage?

It's really not that jarrying in my experience. in my 84 you'd drop the occasional swear word after hitting something gnarly as heck...but in red, I HAD to air down.

It's not a super hardcore trail by any means, but when you hit those soccer ball sized rocks at more than 3mph, you feel it in your back

[blackdiamond [OP]]

It's really not that jarrying in my experience. in my 84 you'd drop the occasional swear word after hitting something gnarly as heck...but in red, I HAD to air down.

It's not a super hardcore trail by any means, but when you hit those soccer ball sized rocks at more than 3mph, you feel it in your back

You do realize that rolling over rocks like that with enough speed to "jar" you means that you're putting unnecessary stress into your rig.  Having soft tires takes the edge off of things which has benefits for both ride quality and wear and tear. Even 15 psi would make a nice difference.

[Rockcrawlintoy]

The nice ride makes a big difference after being on the trail for8 hours

[Snowtoy]

It's really not that jarrying in my experience. in my 84 you'd drop the occasional swear word after hitting something gnarly as heck...but in red, I HAD to air down.

It's not a super hardcore trail by any means, but when you hit those soccer ball sized rocks at more than 3mph, you feel it in your back

A heavy footed buddy has sliced sidewalls on smooth boulders like those both at street psi, and once sliced one on a smooth tree root due to speed and psi.

Back before snow wheeling became popular, most wheelers w/MT's didn't air down below 15psi, it smoothed out washboard forest service roads, allowed the tires to absorb trail impacts and provide better traction, yet still have enough psi to drive 15-20 miles to the nearest gas station. 

If you don't care for slow 12vlt comps, you can build your own C02 system for under $100, with a 20lb tank you could easily get 6-10 trips airing up from 15-25psi depending on the time of year.

[Gnarly4X]

http://www.independent.co.uk/news/science/how-to-convince-some-to-change-their-mind-according-to-science-a6867291.html

[:)bestgen4runner]

Anyone thinking about getting a bigger cam? Just sayin 

[Rockcrawlintoy]

Anyone thinking about getting a bigger cam? Just sayin 

Magic computer chips that boost HP are better

[Gnarly4X]

Magic computer chips that boost HP are better

I think I read somewhere that Nitrogen filled tires will get you an extra 1 or 2 HP? 

Big cams and chips are bogus bling.

Gnarls.

[fasterspider]

I'm gonna chip the carburetor in my 22r, hope I don't break it. 😆

[H8PVMNT]

You should get the supra injectors.

[63W]

The nice ride makes a big difference after being on the trail for8 hours

Agreed.   Give the kid a couple years and he will start airing down, I like to have use of my neck and back the next day.

[300k]

The nice ride makes a big difference after being on the trail for8 hours

Wow. Reading comprehension like the rest of WA boys. Being on a trail with boulders for longer than 2 hours will for sure be an airdown. The Gap you have boulders for 100 yards...not worth wasting my time airing down for 3 minutes of boulders

[Rockcrawlintoy]

I air down if I am gonna be on a dirt road for a while. Rides so much nicer

[SqWADoosh]

Wow. Reading comprehension like the rest of WA boys. Being on a trail with boulders for longer than 2 hours will for sure be an airdown. The Gap you have boulders for 100 yards...not worth wasting my time airing down for 3 minutes of boulders

You couldn't finish high school and you really are going to talk on people with degrees and careers? You are an idiot.

[blackdiamond [OP]]

You couldn't finish high school and you really are going to talk on people with degrees and careers? You are an idiot.

My degree is in radians...

In related news, I purchased a Smittybuilt 12v air compressor. Mostly because I still have not aired up all the way after wheeling with that stupid Jeep.

[300k]

You couldn't finish high school and you really are going to talk on people with degrees and careers? You are an idiot.

Again, reading comprehension. I left BASIS due to extreme left preachings that are usually found on a college campus. I was taking highschool senior level stuff in 5th and 6th grade. I was in Chemistry, biology, physics, calculus, and speaking Latin in 5th grade, and French in the 6th. You don't get into that school by being dumb, but unfortunately unless you think like them, you get nowhere...not that I'd want a free ticket to any of these colleges, I'd probably come out wearing cargo pants, a shemagh around my neck, purple tint glasses and a dumb hat lol!

Today ORM DID purchase a hands free deflator + gauge, so maybe more testing can be done.

[Gnarly4X]

My degree is in Fahrenheit. I Like It Hot!

Gnarls.

[Gnarly4X]

To quote Mark Twain .... "I never let my schooling get in the way of my education."

Gnarls.

[blackdiamond [OP]]

https://www.morris4x4center.com/smittybilt-r-a-d-rapid-air-deflator-kit.html?gclid=EAIaIQobChMIoLqotsvd1gIVSpJ-Ch3Jtw-cEAQYBCABEgLU1fD_BwE&gclsrc=aw.ds

This is the best way to go in my opinion.

[Willard]

Growing up wheeling in a car seat in my dad's FJ40 I clearly remember them airing down always. Funny thing is that back in the day when everyone ran the 36" swamper tsl it was dangerous airing down below 15psi lol. Same with boggers & thornbirds they were bead throwing cork suckers, starting fluid was mans best friend in those days of no beadlocks. This was 25 years ago. But they always aired down regardless of trail and would adjust if needed. One of my best investments was my ViAir OBA kit. Works great....I do need a 2nd compressor now to fill up the 40's lol. Funny someone mentioned dealing with a breakdowns on the trail and time that takes, first day and first time on the Rubicon Labor Day wknd this year on the steps my dad sheared his long side shaft on his FJ rear axle. Down 24 hours and I had to pull the whole 3rd right there while my dad got back and went into placerville and found an axle and had to order a bearing and seal and go back next day for the parts, full tear down next to the steps to get all the metal as well as the spline portion out of the carrier. If you are worried about time consumption of airing down and back up you are in the wrong sport. Always plan ahead and carry appropriate tools, give yourself extra time and carry large quantities of alcohol for breakdowns!!!!!


Sent from my iPhone using Tapatalk

[:)bestgen4runner]

Personally I don’t mind the breakdowns it just adds to the days adventure. No body wants it to happen but it’s inevitable. 

[Gnarly4X]

https://www.morris4x4center.com/smittybilt-r-a-d-rapid-air-deflator-kit.html?gclid=EAIaIQobChMIoLqotsvd1gIVSpJ-Ch3Jtw-cEAQYBCABEgLU1fD_BwE&gclsrc=aw.ds

This is the best way to go in my opinion.

Yeah, that's a nice tool.

https://www.amazon.com/Motion-Pro-08-0183-Valve-Remover/dp/B001KO84I0/ref=sr_1_4?ie=UTF8&qid=1507374341&sr=8-4&keywords=valve+stem+removal+tool

https://www.amazon.com/Accu-Gage-PSI-Dial-Tire-Gauge/dp/B00070KA5I/ref=sr_1_25?ie=UTF8&qid=1507374135&sr=8-25&keywords=tire+pressure+gauges


I tried different gauges over the years.  Ended up with a gauge and core removal tool like the above.

Some guys removed the cores and aired  down in a few minutes.  On highway I ran 20 psi rear and 25 psi front for my 33s, so I could air down in less the 5 minutes.  I could air back up in less than 5 minutes with my CO2 tank.

Some guys had York conversions and tanks, so they’d generously offer to air up anyone else.  Some guys used those little bicycle very low CFM, high PSI 12V compressors, and it would take 30 minutes for them to air back up.  Someone always stayed behind and made sure everyone got back on the road from the end of trail.  Some guys trailered their rigs so they spent their time unstrapping and restrapping their rigs on their trailers.

I’d say that as a general rule we’d be ready to roll within 15 or 20 minutes after stopping at the trail head.  In terms of wheeling time, airing up and down was not even a drop in the bucket, and was as much a part of wheeling as locking in the hubs.

I ran trails for years with guys who had 20 years on me on the trails and only aired down to maybe 20 lbs.  They’d thrash, spin tires, bounce, and throttle jockey their way through the trail, BUT that is the way they liked to wheel.

That’s the great part about the sport and hobby of 4-wheeling, you “run what you brung” and everyone enjoyed it in their own way.  On any given trail run, there could be guys with $5,000 rigs and guys with $50,000 rigs, at the end of the day they both ended up at the end of the trail…. go figure! LOL.

Gnarls.

[Gnarly4X]

... No body wants it to happen but it’s inevitable. 

Yep...  Here in AZ we got into more and more challenging rock crawling trails, damage and breakage was inevitable.

Gnarls.