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Tire Pressure

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Old 02-26-2009 | 04:23 PM
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Default Tire Pressure

I just got my Jeep lifted (RC 2.5) and Mickey Thompson 33" MTZ's on it. Frankly, it rides TERRIBLE, very harsh over the bumps. However, I checked the tire pressure and the shop had it at 65 PSI (which is the spec), I aired them down to 50 and the ride improved. What pressure are you Mickey Thompson folks running at?
Old 02-26-2009 | 05:23 PM
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Originally Posted by Torrin
I just got my Jeep lifted (RC 2.5) and Mickey Thompson 33" MTZ's on it. Frankly, it rides TERRIBLE, very harsh over the bumps. However, I checked the tire pressure and the shop had it at 65 PSI (which is the spec), I aired them down to 50 and the ride improved. What pressure are you Mickey Thompson folks running at?
I don't have MT's but I have 33's and I had the same thing happen whenever I had my new tires installed. The shop had them at 55psi. You'll find guys that say that is the proper psi and others that say you should be running 28-30psi.
Do the chaulk test and you can't go wrong:

Draw a line or two across the tread of your tires. Drive a little (won't take much, a few times back and forth in the driveway for me) and then check you lines. Wearing in the middle; too much air, wearing on the edges, not enough air.

I found even wear at 35psi and it drives and rides great!

Good luck!
Old 02-26-2009 | 06:31 PM
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I have mine at 35 psi. When I dropped down to 30, I lost about a mile per gallon.
Old 02-26-2009 | 06:33 PM
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Originally Posted by Torrin
I just got my Jeep lifted (RC 2.5) and Mickey Thompson 33" MTZ's on it. Frankly, it rides TERRIBLE, very harsh over the bumps. However, I checked the tire pressure and the shop had it at 65 PSI (which is the spec), I aired them down to 50 and the ride improved. What pressure are you Mickey Thompson folks running at?
holy cow, for 33's, you really should be running closer to 28-30psi. let some air out of them tires and enjoy a nice ride that also has a good flat footprint
Old 02-26-2009 | 07:04 PM
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I run my 33s at 35. Anymore than that and it's like you have rocks for tires...!!!
Old 02-26-2009 | 07:06 PM
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Originally Posted by Torrin
I just got my Jeep lifted (RC 2.5) and Mickey Thompson 33" MTZ's on it. Frankly, it rides TERRIBLE, very harsh over the bumps. However, I checked the tire pressure and the shop had it at 65 PSI (which is the spec), I aired them down to 50 and the ride improved. What pressure are you Mickey Thompson folks running at?
Lets get something straight: 65 isn't spec.

If you read your tire it probably says something like 65 MAX PSI. That means "don't go past 65" -- it doesn't mean "inflate to 65".

As WOL said, you want something in the 28-35 range depending on driving conditions.
Old 02-26-2009 | 07:08 PM
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I agree I had the same problem. I am playin around with my tires right now. When I got em installed they had em at 40 and it felt terrible. Especially at really slow speeds. Once I aired em down to 32 and they feel great. I am running 33" BFG KM2's.
Old 02-26-2009 | 07:54 PM
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Originally Posted by JackMac4
Lets get something straight: 65 isn't spec.

If you read your tire it probably says something like 65 MAX PSI. That means "don't go past 65" -- it doesn't mean "inflate to 65".

As WOL said, you want something in the 28-35 range depending on driving conditions.
yes, that means Max PSI at Max LOAD! I will GAURANTEE your Jeep does not come close to Max load. The chalk test is great yes...and you can also calculate your psi...lets see given the max load on their website being 3195 lbs/tire and your JK weighing roughly 6000lbs ...your looking at about 31PSI as a nice appropriate number (my math, 3195 lbs x 4 tires = 12780....6000 / 12780 = 47%....47% of your tires max psi = about 31 PSI)
Old 02-26-2009 | 08:00 PM
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Originally Posted by wayoflife
holy cow, for 33's, you really should be running closer to 28-30psi. let some air out of them tires and enjoy a nice ride that also has a good flat footprint
The master has spoken, I will drop to 30psi tomorrow!

BTW: I used your write up on centering your steering wheel tonight. While it was simple to do, I NEVER would have tried it without such good instructions, thanks a lot for all the you do for your fellow JK'ers WOL!

Old 02-26-2009 | 08:20 PM
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Originally Posted by BlackNorthernJK
yes, that means Max PSI at Max LOAD! I will GAURANTEE your Jeep does not come close to Max load. The chalk test is great yes...and you can also calculate your psi...lets see given the max load on their website being 3195 lbs/tire and your JK weighing roughly 6000lbs ...your looking at about 31PSI as a nice appropriate number (my math, 3195 lbs x 4 tires = 12780....6000 / 12780 = 47%....47% of your tires max psi = about 31 PSI)
Nice, I always appreciate seeing the math work out, but WOL said 28-30, so guess what I am gonna do!



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