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Tire Pressure?

Old 10-22-2010, 07:16 AM
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Default Tire Pressure?

I have 25k miles on a set of Michelin LTX M/S on a half ton Chevy Z71. I don't rotate like I should I'm sure, but this morning I moved them around. I noticed the middle tread of the tire to be a little worn v/s the outside edges. Its like theres a dip in the tire. I run 32lbs in the front, and 30lbs in the rear. I'm assuming this is a pressure problem. Called 2 buddies this am and they both said I have too much pressure. I can see there point. Called the tire shop, they say not enough pressure. The tire is rated @ 65psi cold. I have pumped them up to 45psi. Anybody want to chime in with there opinion? Thanks.
Old 10-22-2010, 07:23 AM
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Look inside the drivers door they have a decal that states the TP. The factory's spend millions on engineering the vehicle and one has to believe TP is very important.
Old 10-22-2010, 07:28 AM
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My truck is rated to have 26psi F and 29 psi R. I said "F-That" from day 1 after reading others who have never run that low a psi.

I think it really depends on what tires one has, the loads one may be carrying, modifications to anything and all that jizz-jazz.

I've been running 35psi all around for over 100,000 miles and for over 50,000 miles on the same Michelin LTX M/S tires you have and have been mint.
Old 10-22-2010, 07:30 AM
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max cold pressure does not take into account the load on the tire. go with the numbers inside the door.
Old 10-22-2010, 08:09 AM
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10-4 the #'s in the door suggest 35psi. That being said the truck came with 265/ 75 R16. I now have 285 /75 R16. Would this suggest any change from the factories decision to run 35psi, being that now I have a little bigger tire? Also this is a daily driver. I have a little jones brothers skiff, but it's located less than 1/4 mile from the ramp, and under 15mph. So may as well assume I never tow. Thanks. Justin
Old 10-22-2010, 08:12 AM
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I've always gone by the assumption that what's on the inside of the door is for the recommended tire. Is your tire the same as recommended? I would think Michelin knows what that particular model runs best at. My one ton truck with 10 ply tires have a max of 70 psi. I always ran them at 55 to 60 psi and got 70K out of whatever came on it new. My 1/2 ton has Michelins (don't know the model offhand), but I run them about 5 psi under max and they've been on for 3 years.

I've had 10's of work vans and always found it best to run about 10psi below max. Lower was for a softer and quieter ride. Higher was for better handling and load capacities.
Old 10-22-2010, 08:20 AM
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Tarheel posted while I was writing. I would never run a tire rated at 65 psi at less than 50 psi (except on the beach). Check with a trusted dealer and maybe the Michelin website has a Q&A.
Old 10-22-2010, 08:36 AM
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First, you are not running oem sized tires so only use what is on the door as a starting point.

Second, it is important to stager the pressures per what it says on the door. In other words, if the door says to run 30psi in the front and 35psi in the rear, no matter what pressures you run, keep that same 5psi diffference front to rear.

Third, if your tires show more wear in the center, you are over inflated! If both sides show more wear then the center, you are under inflated.

The wider you go on tires, the more differences in inflation affect the wear pattern on the face of the tire.

There is no need to run max pressure in a tire, unless you are loading that tire to its max load rating. Over inflation causes a much harsher ride, and shakes things loose in your vehicle. (along with your teeth) Also it changes the way your vehicle handles. Under inflation causes your vehicle to handle much worse! And not keeping the stagger in tire pressure front to rear can also change the way your vehicle handles and stops!
Old 10-22-2010, 08:51 AM
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Third, if your tires show more wear in the center, you are over inflated! If both sides show more wear then the center, you are under inflated....Thats what by buddies told me. I was running 32psi in the front, and 30psi in the rear. So if this is the case, I would need to bring the pressure down to 28psi front, and 26psi rear? Seems to me that will be awful soft, but I'm the tightest man alive, and want to run these $$ tires to the max.

Last edited by Tarheel Brand; 10-22-2010 at 09:50 AM.
Old 10-22-2010, 09:48 AM
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I do not think I would lower it by that much, mabe just go down by 2 psi front and rear, and see how that works for you. One of the things that happens running lower pressures is you are more apt to see side-wall damage. So do not run a reduced pressure to try to even out the wear.
Old 10-22-2010, 02:27 PM
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I would go talk to a different tire dealer (who actually knows what they're talking about) and get an inflation table for your exact tire model & size. The max cold inflation number on the tire is only for when the truck is fully loaded. Running at that pressure unloaded will be miserable and wear on the tire. Look up the front axle and real axle curb weights for your truck (or better yet go get weighed), then compare to the the inflation table. A bigger tire will require less pressure.
Old 10-22-2010, 02:31 PM
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Originally Posted by hhi angler View Post
Look inside the drivers door they have a decal that states the TP. The factory's spend millions on engineering the vehicle and one has to believe TP is very important.
X2, Normally on the inside of the door jam on driver side
Old 10-22-2010, 08:00 PM
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Originally Posted by Severance View Post
X2, Normally on the inside of the door jam on driver side
mine's on the gas cap door FYI
Old 10-22-2010, 09:11 PM
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My truck's "door sticker" says 26 pounds cold, front and rear for 265x70R16 tires. At 26 pounds, the ride is comfortable and the tread mark on the surface is flat,meaning the width of the tire in on the pavement. I do like to run at 30 pounds as the truck rolls a bit better but the middle of the tire does wear just a little faster than the edges. Getting 60,000 miles plus out of the tires is a little price to pay to get a little better mileage on gas IMO.
Old 10-23-2010, 04:27 PM
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If you are running over sized tires, there is a chance that the width of the bead of the tire is significantly wider than the width of the rim. That will pull both beads of the tire towards each other, consequently bending the tread. That would cause the center of the tread to wear faster.
Old 10-23-2010, 04:39 PM
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The first thing you need to do is get a good tire pressure gauge. They can vary quite a lot.
Old 10-23-2010, 04:48 PM
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If you do not have the recommended tires, the specs on the car are meaningless. Middle tire wear is usually overinflated - BTW -

My advice is to rotate clockwise on the starboard side and counterclockwise on port.
Old 10-24-2010, 03:57 AM
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Originally Posted by LoveTheSea View Post
max cold pressure does not take into account the load on the tire. go with the numbers inside the door.
You cant go with the numbers inside the door. The tires on the wifes car call for a max psi of 51, the door states 30. the tire is basiclly flat at 30. I run 48 in them and am very happy, Shoot at 30 the TPS light comes on sometimes
Old 10-24-2010, 07:14 AM
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Especially on trucks, the tire pressures on the door are for FULL RATED CAPACITY! They don't care about tire wear, just lawsuits. If you have enough sense to adjust your tire pressure to compensate for the load, you'll get vastly improved ride quality and tire wear. OVERINFLATION wears the centers.

I've been driving pickups for 30 years. Never had a tire failure, and DO NOT follow the tire pressure recommendations on the door jamb, unless I'm loaded to capacity.

That friggin' tire pressure monitor..nows there's a good idea gone horribly wrong. I can't even reset mine.
Old 10-24-2010, 08:35 AM
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Originally Posted by cayman donzi View Post
The first thing you need to do is get a good tire pressure gauge. They can vary quite a lot.

I went through four gauges before I found two that read ALMOST the same! I really just check by the tire footprint on the ground though.

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