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Old 03-24-2013, 01:18 PM   #1
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Tire pressure?

So i got 33s on mine with a cheap 2 inch lift and the lift is rough as hell the tires are set to run at 35 but iv got them at 30 to try and soften the ride can i go any lower with out taking down my fuel milage or wrecking the walls of my tires

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Old 03-24-2013, 03:23 PM   #2
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28-30 is 'bout where I ran mine way back when. Softened the ride a bit, but dunno about the MPG. Anything less than 23 or so for me made the rig wag a good bit.

Would guess that a big part of how the ride goes is what type of tires you have. Some have harder sidewalls, etc and ride completely differently than others. I'd say give it a shot at slightly less if you'd like and see how it goes. Don't go to far tho...

...to that:
A buddy of mine drove his home after a weekend of trails and forgot to air up before leaving. 400 miles at 10 PSI wasn't fun...wagged all over the place and he couldn't figure out why

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Old 03-24-2013, 03:29 PM   #3
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Yeah. You can run them at 26-28 for on road driving with no bad side effects
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Old 03-24-2013, 08:29 PM   #4
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Yeah. You can run them at 26-28 for on road driving with no bad side effects

x2 I run my 35's at 25-28 for DD. In bad weather (snow, ice) in CO after all, I air down to 15-20 for DD then air back up later. Off-road I go all the way down to 9...no beadlocks.
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Old 03-24-2013, 10:00 PM   #5
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28 on my wrangler mt/r's. I found 26 to be a little squirrely
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Old 03-24-2013, 10:21 PM   #6
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So i got 33s on mine with a cheap 2 inch lift and the lift is rough as hell the tires are set to run at 35 but iv got them at 30 to try and soften the ride can i go any lower with out taking down my fuel milage or wrecking the walls of my tires
This is where your problem most likely is.
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Old 03-24-2013, 10:21 PM   #7
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x2 I run my 35's at 25-28 for DD. In bad weather (snow, ice) in CO after all, I air down to 15-20 for DD then air back up later. Off-road I go all the way down to 9...no beadlocks.
Why would you air down on the roads for snow/ice, that's just a terrible idea.
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Old 03-25-2013, 12:28 AM   #8
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Lowering the pressure increases the amount of tire touching the pavement and thus better traction.
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Old 03-25-2013, 12:32 AM   #9
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Lol....just read two tire sites. tire rack recommends running at higher PSI while the other says you should drop the pressure for the reason I said before.
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Old 03-25-2013, 01:04 AM   #10
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Lowering the pressure increases the amount of tire touching the pavement and thus better traction.
Good for onroad/dry pavement and offroad on the rocks where you want maximum surface area and friction is relatively high. Bad on ice because your decreasing the contact force between the road and tire. Ice has way to low of a friction coefficient for the increase surface area to be better than the lower contact force.

Imagine it this way, what's going to give you better traction on ice, a pizza cutter or a rolling pin?
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Old 03-25-2013, 09:14 AM   #11
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Lowering the pressure increases the amount of tire touching the pavement and thus better traction.
Not where wet roads or snow covered roads are concerned. On wet roads, fatter/lower air pressure tires are like water skis vs. snow skis... wider means the tire will hydroplane/ride on top of the water more readily. For wet road conditions where hydroplaning is a possibility, you want to be fully aired up. The lower the air pressure, the more likely it is you'll hydroplane.

The rule-of-thumb used by pilots for the speed at which when aircraft tires will hydroplane on wet runways is 9X the square root of the air pressure. So if a tire were at 25 psi, it would tend to hydroplane at 45 mph. If the tire was at 36 psi, it would tend to hydroplane at 54 mph. That is a good illustration showing that the higher the air pressure, the higher the speed it will take the tire to hydroplane at.

For roads with up to a couple inches of snow, narrower tires can dig down through the surface snow to the better traction of the pavement below. That's why in areas with lots of snow like Alaska you'll see tall "pizza cutter" tires.

Same with icy roads... wide fat tires will lose traction on ice far more readily due to the reduced pressure each square inch on the tire has against the ice. Like an ice pick (tire studs) has great traction on ice but not a flat frying pan (wide tires).

When you want lower air pressure in snow is when the snow is deep & you need to be able to stay on top of the snow like when you're offroad in deep snow.
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Old 03-25-2013, 11:58 AM   #12
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I think it has more to do with the shape of the contact path too and also the type of tires you use. For example. A snow and ice tire behaves differently than a standard tire.

Drag racers drop pressure for maximum traction routinely too.
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Old 03-25-2013, 08:42 PM   #13
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In a perfect world we'd have a tire for every application, in the meantime we just keep looking making do with the best we can afford...and figure out what works best for each of us...

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