What is the HIGHEST tire pressure you have had a tire bead bust at???

[turbocruiser]

Yes, sort of strange question (so strange I did not know how to word it to make it make sense) and not sure whether this question really goes to 80's (since I'm specifically thinking of the weight of the rig, the typical thirty-three tires, etc), chit chat (since it is minimal tech), or outfitting (since it involves how i set my staun deflators).

Anyways, if you will excuse any misplacement, what I'm asking is what is the highest tire pressure you have had a tire bead bust at? IOW, once when running 12 to 14 psi on my runner, I busted the bead and had to switch to spare tire. But, I never busted it at 16 to 18 for example. When I did bust the bead I was sorta slipping sideways down a really smooth rock. The sidewall folded over slightly and then the bead broke from the wheel.

So, one way to ask is ... with an 80 (preferably armored and loaded) and with 33" tires (revos in this case), what would be the lowest tire pressure I could/should run at to avoid breaking a bead??? Or, IOW, and more specific to my question, if we give as many data points as possible here, we might find several who have broken beads at say 15 psi in which case I would make sure to go no lower than like 18 which is where my staun's are preset to. Instead of finding out that several people (like myself several times in the runner before the bead break incident) where lucky enough to run at such and such a pressure without a problem, I'd rather know real life examples of beads letting loose at specific pressures. Thanks.

 

[CreeperSleeper]

It depends on wieght (like you said), the width of your wheel, the way you drive, etc. Personally, I used to run my J20 w/ 35s on a 15" wheel at 9lbs front and 6lbs rear and never had a problem... That was on a 3/4ton truck that was HEAVY!

 

[cruiserdan]

I run 17 psi with load range D tyres. (305/70/16) I get nervous below that.

 

[IdahoDoug]

Not to rain on this parade, but this will not provide meaningful data and could in fact cause some to underinflate and get hurt or damage equipment.

Whether a tire bead comes loose from the rim is impacted by the following variables:

tire pressure
tire size
tire brand
tire size vs rim width
rim lip design (there are several commonly used in the US)
rim material (painted steel, clearcoated aluminum, uncoated aluminum, etc)
tire age
tire rubber durometer
vehicle weight
terrain type
side angle of terrain
tire mounting technique (dry, wet, lubed, unlubed, etc)
number of times the tire has been mounted/dismounted (they stretch).
temperature (changes with low pressures dramatically in use)


These just came to me as I typed. So a new Super Swamper at 10 psi on a factory rim may never pop off, but a Uniroyal street tire at 20 psi that's been mounted twice before on factory rims might be a safety hazard. There are simply too many variables at work here to draw meaningful data. By that I mean "OK, I'm safe at X psi".

DougM

 

[cruiserdan]

U are just tooooo much like a factory tech geek......

Where did that come from?


oh, wait, U were a factory tech geek........

Bring Bessie to Moab next May and U can test yer theory........ ;p


unless U are concerned about a scratch or two.


Don't worry, I'll spot you on Kane Creek so you will be just fine....

 

[turbocruiser]

Thanks fellas, keep it coming if you do not mind. Doug, I coulda/shoulda stated that these are stock rims, 285/75/16 revos, and a vehicle that is armored (sliders & skids all around, ARB front bumper, etc.) What Dan provided was perfect; a real world number that was safe for him on his rig which I know is heavier than my rig and with tires that are wider than mine. So, no, I'm not gonna go and lower to 10 pounds simply because no one busted a bead above 9 pounds, but, it is a useful data point that I was wanting to ask about. So again, keep it coming if you do not mind. I'd love it if everyone who busted a bead on a stock rim with 33" to 35" tires would share what pressure they were running when that incident occured. Thanks.

 

[scottm]

That reminds me of hearing tires blow at a triathlon. Competitors bumped up the pressure in their bike tires that morning to the max they dared, some overdid it. During the swim volunteers ran around the bikes fixing the flats. Some guys commented they always ran that pressure in races. I guess the tires or rims got old or damaged, or it got warmer, or all the other stuff Doug mentioned.

 

[Fochdog]

I run 20 psi on my swampers & have yet to bust a bead. This seems high but they are a 33x13.50 on a 16x8.0 rim, so I am nervous about this very issue.

With my BFG All Terrains (LT285/75R16) on OE wheels I have gone as low as 12.5 psi on sand dunes without isse. However, I drove very carefully in this condition.

 

[SR.GRINGO]

what would be the lowest pressure on 315/75-16 w/ front ARB, heavy sliders? The tires are "D" class BFG M/T.

 

[Gumby]

I run 13-15 with BFG MTs. 295/75R16. very heavy sliders, ARB, fat ass driver, no winch. Never lost a bead. Never lost one with the GY AT/S either at that pressure and they have a much softer sidewall.

Stock 80 rims have a LOT of bead area. They are a PIA to change tires on.

 

[NW-sickboy]

I lost beads twice on stock 80 series rims with pressure at 12 and 17.... alot of it depends on how the tires are being pulled and flexed.... both times my sidewall was being flexed all the way sideways.... both were on MTR's..... also lost a bead with super swampers at 10 PSI.. getting ready for bead locks...........

 

[hefty_merv]

Depends on what your doing, in the snow I have had it down to 10psi without a problem...

I have also had it in the mud and have broken the bead on three tyres in one day all about the 20psi range.

If I am going to be doing mud work, I dont go below 25psi, as for sand and snow which are fairly similar in my mind I use about 15 to 20psi and if I get real stuck then down to 10psi till I get out of trouble....

I was a bit scared of lowering them below 30psi when I had 3 in a day for a while, but since lowering them to 10 and not having a problem has overcome my fear...

 

[Bryan E.]

I blew a tire off the bead on my Dad's GMC p/u when I was in highschool. It had full air pressure so was about 32psi. Hit a patch of ice going about 50 mph, slid and slid correcting but the back end finally came around when I hit the dry pavement and tire blew off the bead. Damm teenage drivers!

 

[IdahoDoug]

Brian,

Reminds me of a "testing" incident I had at the GM Proving Grounds about 20 years ago. We were evaluating various AWD vehicles from around the world on artificial ice. The patch of artificial ice was about a quarter mile on a side on a much larger area of blacktop (think 7 miles on a side). Late in the day, things got to a little horsing around and I was curious to see if I could manage to spin a German spec Audi Quattro in a complete 360 before popping off the artificial ice on the other end, so I arrived at the ice patch going around 80 thinking I could gently arc it. Instead, I got into the ice for about 200 feet before the arc disappeared and I was heading for the edge in a straight line with the car perfectly sideways. I thought I was gonna flip it and reflexively bent down, abandoning any attempt to steer or even watch what was about to happen. Hit the dry pavement (hot summer day - extremely grippy) and the car simply went over onto the bump stops for about 150 feet perfectly sideways. My mistake was about halfway through the slide when I figured it was going to work out OK so I sat up and was rewarded with a fine mist of hot melted rubber that was backwinding through the open windows and coated my snappy starched white exec shirt. Those little rubber particles uniformly coated it and I could never get them all out. For years, I wore that shirt with little flecks still stuck to it and it was my "Audi shirt". Heh - thanks for the memory.

Anyhow, this data is all over the map in terms of variables and I just want people to understand that there is statistically zero correlation between on person's experience with low pressures and anothers. We didn't even get into things like "My stock unlocked 80 tire/wheels lasted for 4 days on end at 18psi doing Porcupine Rim, Poison Spider, Moab Rim and Fins-n-Things" vs another guy with the identical rig with lockers pulling two tires off rims trying to get up Potato Salad hill. Just way too many variables for this to be useable.

Danny-boy,

I'd trust you to spot me anywhere I'd turn a wheel, but I've got news for you. Bessie's not going anywhere near Kane Creek. She's my girl and she's been all over Moab and the deserts of SoCal but that's just too much for me to subject her to. I would literally buy ANOTHER 80 to build before I'd do that to the vehicle that's carried both my kids home from the maternity section of the hospital. Believe me, she's been wrung out about as far as a stock, locked 80 will go and that's some pretty hairy terrain. Thanks for the offer, however, and I hope to share a campfire with you in Moab.

Rgds,

DougM

 

[SR.GRINGO]

Potato Salad hill