MAX PSI???????
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Elder User
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MAX PSI???????
It seems some tire dealers are not clear if the max psi rating of a tire is determined when a tire is installed on a wheel and not installed on vehicle OR when a tire is installed on a wheel and on a vehicle and the vehicle is loaded with a certain amount of weight over a certain axle. Just to be clear here is an example, if my tire dealer installed 4 brand new tires on my truck and he inflated all the tires to max psi before re-bolting them to vehicle. If I had heavy load over my rear axle and the rear tire psi exceeded max psi rating, would my rear tires be overloaded?? Tell me what you think.
Thanks
Thanks
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Joined: Apr 2005
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Temperature and altitude will change tire pressures. This will vary a few pounds either way.
The normal procedure is to check your tires when they are cold (having not moved in several hours). Yes, as the tire warms pressure will increase a few psi. This will not hurt the tire. Tire engineers have taken this into account while designing the tire.
Conversely, if the tires were checked at 50*F, then rechecked at 20*F, you will see a lower reading.
This also occurs when changing altitude. If you aired up your tires while at 5,000 ft, then drove to sea level, you will find that you are down a few psi. Going from sea level to higher altitudes will increase psi.
The only time this will really effect tire performance and durability, is if your vehicle is loaded to max (or over) the tire ratings.
Good luck
The normal procedure is to check your tires when they are cold (having not moved in several hours). Yes, as the tire warms pressure will increase a few psi. This will not hurt the tire. Tire engineers have taken this into account while designing the tire.
Conversely, if the tires were checked at 50*F, then rechecked at 20*F, you will see a lower reading.
This also occurs when changing altitude. If you aired up your tires while at 5,000 ft, then drove to sea level, you will find that you are down a few psi. Going from sea level to higher altitudes will increase psi.
The only time this will really effect tire performance and durability, is if your vehicle is loaded to max (or over) the tire ratings.
Good luck
Elder User
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Like others have said, psi will change slightly due to weather conditions and heat from rolling. Not a big deal. What you need to worry about is that the vast majority of tire shops will mount a truck tire and only air it at around 40psi. Thats because they are used to doing car tires all day long. Either tell them to put the correct amount of air in, or do it yourself, but in no way should a HD truck tire be aired that low.
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No this has never happened to me, but a tire dealer could not give me a definitive answer. It just seems to me that in the world of physics, if volume is unchanged then pressure is unchanged. When a tire is heavily loaded the tire is not squeezed, instead it is deformed therefore maintaining the same volume and pressure. I think this is what tires are engineered to do, flex but do not stretch. I think I am making sense, I think everbody agrees. I wonder why a person who works with tires all day would not know the answer????
Thanks for your responses.
Thanks for your responses.
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From: Itinerant
No this has never happened to me, but a tire dealer could not give me a definitive answer. It just seems to me that in the world of physics, if volume is unchanged then pressure is unchanged. When a tire is heavily loaded the tire is not squeezed, instead it is deformed therefore maintaining the same volume and pressure. I think this is what tires are engineered to do, flex but do not stretch. I think I am making sense, I think everbody agrees. I wonder why a person who works with tires all day would not know the answer????
Thanks for your responses.
Thanks for your responses.
. Some do this and then spew info like it's the word
. Remember the best consumer is an informed consumer. Research, research, research. 
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Elder User
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Scraprat, you are soooo right!!!! You would not believe how many 2nd visits back to the shop I have had to make, because I found something that was not done to spec. I am tired of telling people how & when to do their job!!!!!! Maybe one day I will muster up the courage to do my own truck maintence & repairs.
