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Desert Scruff

Air Pressure

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That's one of the reasons you see so many rollover accidents on the highway right when the temps start to get up there. People just don't check their tire pressure when the weather starts getting hot, and if you are at your max in the colder months you're asking for a blow out when things heat up.

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I set my PSI by looking at the dust on the tread after a wash and adjust up or down for even wear across the tread. I normally end up with 35 PSI.

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That's one of the reasons you see so many rollover accidents on the highway right when the temps start to get up there. People just don't check their tire pressure when the weather starts getting hot, and if you are at your max in the colder months you're asking for a blow out when things heat up.

I think, some clarification would be in order regarding tire pressures and resulting tire failures...

 

For moderately over-inflated tires (i.e.: inflated to or moderately in excess of the rated max load pressure), it would be EXTREMELY rare, that over-inflation would cause a blow out...

 

While an over inflated tire is more susceptible to puncture, unless it were either;

A- WAY over-inflated (i.e.: well beyond the tires structural integrity... note: large truck tires are designed to be inflated to 100 psi or higher...)

B- a tire which had been previously damaged or aged beyond it's structural materials limits... OR

C- a tire which was leaking/punctured which allowed the pressure to drop sufficiently for the sidewall to flex enough for it to fail...

 

By far, the most significant reason for a tire blow out is UNDER inflation of the tire. When UNDER inflated, the sidewall of the tires is allowed to flex sufficiently, that it heats up (similar to a coat hanger wire when bent back and forth rapidly), and this flexing heats the materials of the sidewall to the point that the sidewall's structural integrity is compromised enough for it to fail catastrophically...

 

;)

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My oppologies on the misinformation. I'm originally from the Midwest and the excessive heat is usually not a problem. My buddies have been telling me that over inflation is the biggest issue with the heat. Sorry about that, you learn something new every day!

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I too have a 2010 Rubicon. I have been running the tires from day one @ 37 PSI for pavement use and have no problems. I run the tires at ~ 17 PSI when off road, again no problems. I have 41K on the tires and they have ~ 8/32" tread remaining. I just changed them out as I am going on a 3K mile road trip and felt the sidewalls are too beat up with rock damage for that long a trip. The tires I put on are the exact same BFG mud terrains with a little more tread (~10/32 each).

 

what I found when putting on the new used tires was they make much much more noise when rolling then my original tires.

 

Is this due to the previous owner not setting the tires to the proper tire pressure and/or not rotating the tires every 3K miles like I do? My old tires roll so much more smoothly and very quite compared to these replacements I have on now.

~Jim

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For factory tires I use the door tag recommendation....... But for after market tires that tag is no longer valid so,

 

What I do is Take a piece of chalk (I stole one of those BIG chalk sticks that my kid used to draw on the sidewalk with ;))

Then I draw a thick line across the treads of my tires, I get in the Jeep and make a pass or two in front of the the house or up and down the driveway.

If the chalk is evenly wore off all the way across the tread the pressure is correct for the weight of the vehicle with the tires on it. If its only wore off in the middle of the tread the tire is over inflated, If the outsides but not the inside is wore off the tire is under inflated and I adjust accordingly until the chalk line is wore off evenly. At that point I know the correct pressure for the weight of my vehicle and tire combination.

 

I do this both with the Jeep empty (city and D.D. driving) and fully loaded for a long trip.

 

It can be a little bit fiddley, back and forth But when its done I know exactly where my tire pressure should be.

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I too have a 2010 Rubicon. I have been running the tires from day one @ 37 PSI for pavement use and have no problems. I run the tires at ~ 17 PSI when off road, again no problems. I have 41K on the tires and they have ~ 8/32" tread remaining. I just changed them out as I am going on a 3K mile road trip and felt the sidewalls are too beat up with rock damage for that long a trip. The tires I put on are the exact same BFG mud terrains with a little more tread (~10/32 each).

 

what I found when putting on the new used tires was they make much much more noise when rolling then my original tires.

 

Is this due to the previous owner not setting the tires to the proper tire pressure and/or not rotating the tires every 3K miles like I do? My old tires roll so much more smoothly and very quite compared to these replacements I have on now.

~Jim

Without seeing your replacement tires, it is difficult-to-impossible to know for sure, however, I suspect that either; they were not rotated, the alignment may have been slightly off, or perhaps tire pressures may not have been properly monitored.

 

In any event, all of the above can lead to un-wanted tire wear, such as cupping, and/or feathering of the tread, which in turn can create annoying noise, and increase rolling resistance.

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Ob1jeeper, so if the Jeep is aired down to say 20 pounds, but you to go out to pavement, drive 5 miles before going offroad again, and kept your speed at, say, 25 mph or under, will that cause any problem--or should the Jeep be aired up and aired down? Is speed the issue more than the distance on pavement?

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I too have a 2010 Rubicon. I have been running the tires from day one @ 37 PSI for pavement use and have no problems. I run the tires at ~ 17 PSI when off road, again no problems. I have 41K on the tires and they have ~ 8/32" tread remaining. I just changed them out as I am going on a 3K mile road trip and felt the sidewalls are too beat up with rock damage for that long a trip. The tires I put on are the exact same BFG mud terrains with a little more tread (~10/32 each).

 

what I found when putting on the new used tires was they make much much more noise when rolling then my original tires.

 

Is this due to the previous owner not setting the tires to the proper tire pressure and/or not rotating the tires every 3K miles like I do? My old tires roll so much more smoothly and very quite compared to these replacements I have on now.

~Jim

 

As long as your newer tires are not a different load range than the originals, i would guess either that or the newer ones may have sat a while before being reused, perhaps subject to a little dry rotting.

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Ob1jeeper, so if the Jeep is aired down to say 20 pounds, but you to go out to pavement, drive 5 miles before going offroad again, and kept your speed at, say, 25 mph or under, will that cause any problem--or should the Jeep be aired up and aired down? Is speed the issue more than the distance on pavement?
For typical Jeep tire sizes and applications, I see no problems with your described scenario... Lowering tire pressures for improved puncture resistance, off-road ride comfort, and traction is a normal, and desirable.

 

There are a number of factors that can come into play when we select how far to lower tire pressures for off-roading. Ambient temps, tire load ratings and size, vehicle weight, wheel width, wheel type (bead lock or not), type of offroading, etc., etc.

 

Lowering to as low as 3-5 psi, may be OK... particularly if you are still talking about limited pavement use when speeds of 45-50 mph or lower, and may be fine for up to 40-50 miles or more, depending on a host of the above factors and ambient temperature, weather, and road conditions.

 

Tire wear at reduced inflations will suffer, particularly during extended uses, but most off-roaders accept that, and find that the costs associated with these increases in wear are offset by a reduced overall suspension spring rate as the result of lowering tire pressures, which in turn factors in to providing improved overall vehicle reliability and durability, as the impact loads and natural frequencies of the suspension are reduced at lowered tire pressures...;)

 

Hope this helps explain some of the reasons behind why many experienced off-roaders lower tire pressures for off-pavement running.;)

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