psi question
12 Second Club
Joined: Feb 2006
Posts: 993
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From: Waukesha,WI
i used to work at a tires store and you wouldn't believe how many people come in because there tire light is on. goes like this. "i just put air in my tires because they looked low and now my tire light came on." how much air did you put in the tires? "oh well i put in what it says on the side wall." thats not the correct pressure for your vehicle you just voided your tire warranty. 
lol
lol Why would putting what the tire manufacturer says is ok (I agree it is the max, but) void the tire manufacturers warranty? I've never had a tire rep even bring up air pressure unless they were denying a claim due to low air pressure wear.
On The Tree
Joined: Jun 2008
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But you didnt finish the statement on the sidwall of the tire. It states " Tire failure due to underinflation/overloading --- Follow owners manual or tire placard in vehicle". The vehicle manufacturers put these pressures on the placard to provide best all around performance. Meaning the combination of ride quality, handling and fuel economy. Its different for every vehicle. A 1990 Mazda miata placard states 26 psi cold. A 2005 GMC Sierra 2500 diesel states 60 for the front and 80 for the rear tires. All based on weight and loading. Try switching the two placards between the two vehicles and see how well it works. The only time I've felt the placard was wrong was with Ford Explorer/ Mazda Navajo.
The whole Firestone tire debacle. The placard stated 26 psi! On a 4,000 lb vehicle! No wonder the tires blew out and caused roll overs. Everyone is entitled to their opinions, absolutely. But I dont understand why you would ignore what the vehicle and tire manufacturers/engineers have studied, tested and concluded is best for your vehicle? As stated before, follow the placard or owners manual. The owners manual does state increasing the pressures for high speed driving, BUT NOT TO MAX.
The whole Firestone tire debacle. The placard stated 26 psi! On a 4,000 lb vehicle! No wonder the tires blew out and caused roll overs. Everyone is entitled to their opinions, absolutely. But I dont understand why you would ignore what the vehicle and tire manufacturers/engineers have studied, tested and concluded is best for your vehicle? As stated before, follow the placard or owners manual. The owners manual does state increasing the pressures for high speed driving, BUT NOT TO MAX.
I have no issues whatsoever with running pressures that the placard says, and by all means run what works for you (anyone). My statement is simply that the max has worked very good for me (I prefer it over the 30psi on the placard), I'm satisfied with the ride, wear, etc.. What I don't understand is the feelings of impending doom, or ignorance of people who run more than the placard recommends.
Last edited by rnl35thss; Apr 27, 2010 at 03:59 PM.
TECH Regular
Joined: Aug 2008
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Read your owner's manual, people.
The tire pressure on the sidewall is the "limit" not the standard inflation pressure, because that may vary from car to car. Go with what it says in the owner's manual or the door placard. That's what the car was designed to run with.
The tire may also be rated for 150 MPH, but that doesn't mean you should always drive 150 MPH - only that it's the maximum the tire is rated to withstand under normal conditions.
The tire pressure on the sidewall is the "limit" not the standard inflation pressure, because that may vary from car to car. Go with what it says in the owner's manual or the door placard. That's what the car was designed to run with.
The tire may also be rated for 150 MPH, but that doesn't mean you should always drive 150 MPH - only that it's the maximum the tire is rated to withstand under normal conditions.
Douchebag On The Tree
Joined: Nov 2009
Posts: 1,268
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From: Indianapolis, IN
Not trying to start any pissing contest, I agree with a lot of what you are saying, but not quite sure what the little head shake is for. You are completely entitled to your opinions. Air pressure is something that can vary from situation to situation. I don't think there is anything wrong with running as low as 30psi if that suits the situation. I've logged close to a million miles on my vehicles running pressures as stated earlier without problems, maybe that is what has me a little huffy. Air pressure relates DIRECTLY with load. (go ahead read the tire) Max load XXX @ Max Pressure XXXpsi. The folks that engineer the tires are quite aware that tires build heat, which results in increasing pressures so to say protecting themselves from people who don't have a clue is simply wrong. Again, read that sidewall, and placard those pressures are cold.The protecting the rims thing, run a different tire (more sidewall). I do have to change one of my statements though, I know of one tire failure due to overinflation, it was a implement tire with a max press rating of 14 psi. the knucklehead put 85 psi in it, it split the sidewall. Also looking at the placard on the door, under it it states for higher speeds to consult manual for pressure recommendations. Everytime the contact patch is on the ground, the sidewall flexes. Increase the rate and thats alot of flexing which = heat, which is bad for the tires (why you up pressures w/ speed/load). Read that sidewall again, every passenger car tire I've ever seen says "safety warning: serious injury may result from: tire failure due to underinflation/overloading:....."
Sorry for the long post, but I feel better now. Best wishes.
Sorry for the long post, but I feel better now. Best wishes.
Also, like I already said, opinions are one thing, but this is a situation where there is a right way and wrong way to do something. The gray area is very thin...and running MAX psi is not in said area.
Simple science (which you seem to have a good grasp on) is how the manufacturers come up with the recommended psi's. This science goes against running at the high of a psi...that is unless you car is in perpetual motion at 150mph and you just hop in and out when you need to go somewhere.
Douchebag On The Tree
Joined: Nov 2009
Posts: 1,268
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From: Indianapolis, IN
I feel like this thread is turning into a "but I run 315's on my 9.5 inch wheels with no problems!" thread, and it should be locked just the same in order to save people of misinformation.
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Douchebag On The Tree
Joined: Nov 2009
Posts: 1,268
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From: Indianapolis, IN
Do car-savvy people everywhere a favor and trade in your camaro for a jetta, put on "rims" and tires with a thin sidewall so you have a reason to run 51psi, and throw out your camber like a VIP. (I bet you think you'll have even tread wear then, too!)
Did I mention you're still doing it wrong?
I'm walking away agreeing that when recommending air pressures always follow tire placard, but I and others I know and apparently 51psi guy, have had too much success with higher air pressures to walk away saying we've been doing it wrong all along. I can agree to disagree. Enjoyed it guys.
Douchebag On The Tree
Joined: Nov 2009
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From: Indianapolis, IN
Joined: Aug 2007
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From: Turnin' Wrenches Infractions: 005
hey. read my posts. Im just saying what I do and what I will continue to do. Did I once start calling anyone names or saying anyones wrong? I just said what I do and thats it. So chill with the hate pal. Theres nothing more childish than hating someone for their opinion. Also,over inflation can also be determined by over inflating the max and not your opinion of the door sticker. Ever think of that? So I am technically properly inflated but just to the max. Like I said,just my opinion,no need for name calling.
To the other guy....are you saying im rice and have a mullet because I have my tires at the max psi? Whats the logic behind that one?
To the other guy....are you saying im rice and have a mullet because I have my tires at the max psi? Whats the logic behind that one?
Don't sweat it man, run what works for you. Max works and has worked just fine for me too. I prefer the crisper response. I don't understand the name calling and stuff. It also seems as if there is a fear of messing with air pressures. Oh well, thats what makes the world go around.
TECH Regular
Joined: Aug 2008
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I just said what I do and thats it. So chill with the hate pal. Theres nothing more childish than hating someone for their opinion. Also,over inflation can also be determined by over inflating the max and not your opinion of the door sticker. Ever think of that? So I am technically properly inflated but just to the max. Like I said,just my opinion,no need for name calling.
If you have a bolt that can withstand 500 lb-ft and the torque spec for the part is 100 lb-ft, what do you torque the bolt to?
If you are at the maximum inflation pressure of the tire, you are within the spec of the tire, but you are out of spec for that particular installation on the car. Run what you want to run, but do so knowing the potential risks. Just as many people run 315 tires on 9.5" wide wheels and say it's fine, their "opinion" is outside the manufacturer's design specification and just because they haven't had a catastrophic failure yet doesn't mean it's safe.
Thats fine. However you wanna see it. I agree with you about the bolt,but its not a bolt,its tires that are only inflated to the max psi big difference. Whatever. Debate what I say all you want. Bottom line is my tires are at max psi. Also, its obviously a matter of opinion if you have different people running different pressures and thats a fact. Theres nothing wrong with running your tires at max psi. Have a great day.
Something I didn't think about, I hope everyone swearing by the placard is running stock wheels and tires (preferably with the proper TPC spec) since that is what the engineers at the manufacturer intended in their design. (no mine aren't stock either) I would venture to say a large percentage of folks on this site are passionate about our cars, and have modified and adjusted on them to suit our personal needs, expectations, and desired performance. To ignore an adjustment as easy and as effective(not quite night and day, but noticeable) as air pressure, and feel they are bound by a sticker just seems to boggle my mind.