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Unread 05-27-2005, 01:39 PM   #1
bulldog
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Default Site on why and how to air down your tires

Very informative on the advantages of airing down and how much.
http://4x4now.com/sfjun96.htm
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Unread 03-07-2008, 08:10 AM   #2
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^^^^^^^^^^^^^^^^^^^^^^



Thats really good.

I used to think dropping from 37psi to 20 psi was "good enough" for the sandy sections.

Next time I will try a drop down to 10 psi

then drop down to 7 ~ 8 psi

Like you say,

Just have a good compressor to blow them back up again !

G.
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Unread 03-07-2008, 11:21 AM   #3
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Originally Posted by uk_vette View Post
^^^^^^^^^^^^^^^^^^^^^^



That's really good.

I used to think dropping from 37psi to 20 psi was "good enough" for the sandy sections.

Next time I will try a drop down to 10 psi

then drop down to 7 ~ 8 psi

Like you say,

Just have a good compressor to blow them back up again !

G.

Or a full Co-2 tank!!!
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Unread 03-07-2008, 12:00 PM   #4
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Or a full Co-2 tank!!!
CO-2 tanks will definitly fill your tires up, quick too, even from 8 p.s.i.
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Unread 03-07-2008, 12:33 PM   #5
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Good link. I have read it before. Based on such advice, I have always aired my tires down to about 10-12 psi on sand, but one things I have always wondered is if the sidewall flex can be detrimental. Underinflated tires cause excessive sidewall flex and can cause the tire to fail (e.g. the infamous Ford Explorer debacle). On the sand, speeds aren't as high as the highway, but you can drive pretty fast for pretty long in some open areas. Its even easier with low pressures as you just glide over the sand like the article says. Any worries about overheating the sidewalls and damaging the tires? I tend to hold back on my speed when my tires are aired down, even though I could safely go 40-50mph. This is really only a concern on sand as in the rocks speeds are much slower.
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Unread 03-07-2008, 01:31 PM   #6
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Originally Posted by jbs11 View Post
Good link. I have read it before. Based on such advice, I have always aired my tires down to about 10-12 psi on sand, but one things I have always wondered is if the sidewall flex can be detrimental. Underinflated tires cause excessive sidewall flex and can cause the tire to fail (e.g. the infamous Ford Explorer debacle). On the sand, speeds aren't as high as the highway, but you can drive pretty fast for pretty long in some open areas. Its even easier with low pressures as you just glide over the sand like the article says. Any worries about overheating the sidewalls and damaging the tires? I tend to hold back on my speed when my tires are aired down, even though I could safely go 40-50mph. This is really only a concern on sand as in the rocks speeds are much slower.
.
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Hi JBS11

I don't think I would drive any thing like them speeds, 40 ~50 mph. with just 10 ~ 12 psi in the tyres.

No way on earth ! Imagine being 200 miles in an African desert, and damn bead pops off the rim .

Slow and easy for me.

Just too easy for a bead to pop off the rim.

thats just asking for a whole lot of trouble.

I would play safe and stick to around 20 mph. Might be slow, but I would get there in the end.

it would also help any side wall overheating that would occur.

Graham
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Unread 03-09-2008, 04:52 PM   #7
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.
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Hi JBS11

I don't think I would drive any thing like them speeds, 40 ~50 mph. with just 10 ~ 12 psi in the tyres.

No way on earth ! Imagine being 200 miles in an African desert, and damn bead pops off the rim .

Slow and easy for me.

Just too easy for a bead to pop off the rim.

thats just asking for a whole lot of trouble.

I would play safe and stick to around 20 mph. Might be slow, but I would get there in the end.

it would also help any side wall overheating that would occur.

Graham
That's how I've always felt, so I tend to stay pretty slow. I was just wondering if mine is a valid concern, and its seems you agree it is. I see these pictures of people getting air on dunes out in CA. They must be going a lot faster than 20mph, so maybe the tires aren't aired down as far (harder/packed sand?) Maybe in such situations, and on sandy/washboard dirt roads, tire pressures in the 20-25psi range are OK, so speeds can be a lot higher?
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Unread 03-09-2008, 05:11 PM   #8
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I have ran at Pismo with the P rated Revo ATs at 12 PSI normally and we hit speeds in excess of 60 MPH. Onnly thing to wath out for is popping a bead, but the soft sand help keep the tire just fine without issues. I ran 25 PSI with the same tires fro normal rocks and washboards roads like Death Valley and worked fine.

With the Toyo MTs (Load rated E) which have a much stiffer sidewall and larger tires, I run 10 PSI on the dunes (woudl run lower if I had beadlock wheels) an 16-17 PSI on rocks, etc.

So it really depends on the tire size, sidewall stifnnes and vhecile weight to get the right balance. If you have bead lock wheels you can even go a bit lower.

Soft sand is a far different issue than harder surfaces and going really low doesn't seem to affect the zillions of folks runnign on dunes here. At worst they pop a bead due to lack of beadlocks and/or doing supid stuff like donuts to show off ( me )
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Unread 03-09-2008, 07:06 PM   #9
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One thing I found was that lower the psi often led to unbalanced tires. I think probably because they shift on the rim somewhat, especially under hard cornering in the sand where there can be a lot of resistance to the tire.

Just my experience, yours might vary.
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Unread 03-11-2008, 03:22 PM   #10
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One thing I found was that lower the psi often led to unbalanced tires. I think probably because they shift on the rim somewhat, especially under hard cornering in the sand where there can be a lot of resistance to the tire.

Just my experience, yours might vary.
Very true. I usually make a small mark with a Sharpie or paint pen on the tire and rim so I can see if they have shifted and if I should expect to need to get them re-balanced.
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Unread 03-11-2008, 10:32 PM   #11
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Neat idea jbs11!
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Unread 02-12-2010, 12:55 AM   #12
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Quote:
Originally Posted by jbs11 View Post
Good link. I have read it before. Based on such advice, I have always aired my tires down to about 10-12 psi on sand, but one things I have always wondered is if the sidewall flex can be detrimental. Underinflated tires cause excessive sidewall flex and can cause the tire to fail (e.g. the infamous Ford Explorer debacle). On the sand, speeds aren't as high as the highway, but you can drive pretty fast for pretty long in some open areas. Its even easier with low pressures as you just glide over the sand like the article says. Any worries about overheating the sidewalls and damaging the tires? I tend to hold back on my speed when my tires are aired down, even though I could safely go 40-50mph. This is really only a concern on sand as in the rocks speeds are much slower.
In the sand you don't have to worry about the sidewall heating up as much as you would on the highway. The sand 'gives' and flexes with the tire. Usually when you are in the sand it's either at the beach or desert in the winter so ambient temps are much lower than the blacktop would be as well.

One important point to remember is don't be a jackass doin fish tails! The amount of pressure in the tire is how much pressure holding the bead to the rim, meaning if you have 3 psi that means there is 3 pounds of force seating that bead!

I have popped a bead a couple times but it was always because I was being a jackass! Nothing a jack and air pump couldn't fix.http://www.youtube.com/watch?v=7NQfo0Ih1gk
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Unread 02-12-2010, 01:37 PM   #13
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Quote:
Originally Posted by bulldog View Post
I have ran at Pismo with the P rated Revo ATs at 12 PSI normally and we hit speeds in excess of 60 MPH. Onnly thing to wath out for is popping a bead, but the soft sand help keep the tire just fine without issues. I ran 25 PSI with the same tires fro normal rocks and washboards roads like Death Valley and worked fine.

With the Toyo MTs (Load rated E) which have a much stiffer sidewall and larger tires, I run 10 PSI on the dunes (woudl run lower if I had beadlock wheels) an 16-17 PSI on rocks, etc.
Do you have any experience airing down the stock tires that came with your 4Runner,
or did you replace your tires right away? I'm still using the Michelins that came with my
4Runner and I'm not sure how much they can be aired down.
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Unread 02-12-2010, 01:43 PM   #14
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I wouldn't trust stock tires on any terrain that you'd need to air down for.
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Unread 02-12-2010, 01:57 PM   #15
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So you're saying "Don't air down stock tires"?

I drove Robert's Mojave trek (Sept '08) with my stock tires at full pressure.
Most of the others aired down. So the stock tires are capable of some off road driving.
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Unread 02-12-2010, 02:15 PM   #16
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I would air down stock tires a little, it make shtem a bit softer and prevents punctures. Airing them down too much will actually expose the sidewall and cause failure as well.

Around 25PSI is a good pressure I found for stock and 32" non LT AT type tires. It conform a little, but not too much.

We actually took Expat up Gold Mountain with his stock Dunlops. A few years later (yeah the trail was worse) some folks blew out AT tires.
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Unread 02-12-2010, 02:43 PM   #17
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Quote:
Originally Posted by Mikestang View Post
I wouldn't trust stock tires on any terrain that you'd need to air down for.
sand?
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Unread 03-30-2015, 08:41 AM   #18
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The link seems broken now but the page is still in The Internet Archive: http://web.archive.org/web/201304030...om/sfjun96.htm
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