A set of tires, inflated at the maximum allowed PSI on the sidewall (e.g. 44PSI), is less likely to blow out during high speed driving on a hot day, vs. a set of tires, inflated at a lower, vehicle manufacturer recommended pressure(e.g. 35 PSI). Same load condition is assumed.
True or False?
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I'd say lower pressure will build more heat and blow out first.
So true.
bruce
Alright, I'll play devil's advocate: The sidewall on a tire pumped up to the max will be more vulnerable to damage from road hazards. False.
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The maximum psi marked on the tire refers to maximum cold pressure.
The inflation recommended by the vehicle manufacturer is certainly within in the safe range. For example, my manual calls for 32 psi. I go for 36-38 psi, depending on where and with how many people or cargo I drive around. Those tires have a maximum allowed inflation of 51 psi.
Just for background:
Static bursting pressure for passenger car tires is well over 100 psi. What is written on the sidewall is the maximum USAGE pressure.
So what causes tires to blow out? Road hazards!!
And lower pressures will cause the tire to be more flexible and more likely to deform and therefore, less likely to blow out!
BUT - if you go too low, the tire is more likely to bottom out against the rim, and that impact ould cause a blowout.
So the answer is - it depends on whether you are talking about an impact with an object that would cause the tire to bottom out - like a curb (a common problem with super low profile tires) OR the tire is encountering an object in the road (like a pointed rock) and the tire is not going to bottom out against the rim.
I'll add that long distance, higher speed driving requires higher tire pressures anyway. Some sources say that if you plan on taking a long highway trip, you should add pressure depending on the speed rating of your tire.
I would see no issue with max sidewall psi (Did a trip from SC to NY with 44 psi.) as long as, like Capriracer said, you had no major obstacles to avoid.
I would also see no issue with a 35 psi tire under the same circumstances. I have run patrol car tires at both psi's and never had a blow out.
I have had a number of tires blow out and not all of them have been road hazards. In one case, a bad alignment job caused the inside edge of a tire to quickly wear through until it blew in the stress of a bend going up Pike's Peak. I once made the mistake of buying some cheapy Jetzon tires. One of them blew after the sidewall cracked.
I am suspicious about a couple of other tires that went bad. They developed a soft spot in the sidewall. Of course, the dealer insisted it was ''road hazard'' and denied warranty.
In one road hazard encounter, the rim bent enough to blow the tire, but the tire survived. Same for about a dozen other people gathered in the gas station a block down the road. The kid was ripping off tires, pounding out rims, remounting the tires as fast as he could. He was charging the 1972 rate of $2 for mounting a tire. Bet he couldn't move the next morning.
Maybe the kid's friend was responsible for creating the road hazard in the first place. You know... he needed to create some customers. ![[Smile]](images/icons/smile.gif)
My car's owner's manual and the sticker on the door both indicate higher tire pressure for prolonged driving at high speed.
My own observations are that underinflated tires get REALLY hot really fast - and heat does the damage.
Cheers
JJ
I'll say true even though some crucial information is missing.
What is the OCI and the color of the car?
Just kidding, but I will say true based upon the same reasons stated by Bruce.
I think it's true due to the fact that lower pressure causes more sidewall bulge due to the weight on it and as the tire spins the walls are flexing out at the bottom causing friction and heat, damaging the tire and increasing blowout risk.
quote:Won't the pressure go up anyway under these conditions, due to heat, or doesn't that count? Maybe a dumb question but that's how I learn.
Originally posted by wantin150: I'll add that long distance, higher speed driving requires higher tire pressures anyway. Some sources say that if you plan on taking a long highway trip, you should add pressure depending on the speed rating of your tire.
![[Razz]](images/icons/tongue.gif){kind=icon}
quote:That additional increase in psi due to heat may be factored in with the recommendation for added psi before starting. Someone else can probably tell you the max increase but I have usually observed an increase of 4-6 psi after driving long distances. I'll try to find the link to the info and post it. http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=72 http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=147 [ September 14, 2006, 09:25 AM: Message edited by: wantin150 ]
Originally posted by user00000:quote:Won't the pressure go up anyway under these conditions, due to heat, or doesn't that count? Maybe a dumb question but that's how I learn.
Originally posted by wantin150: I'll add that long distance, higher speed driving requires higher tire pressures anyway. Some sources say that if you plan on taking a long highway trip, you should add pressure depending on the speed rating of your tire.
If you take the road hazard out of the question, I think in a perfect world, the chances would be identical if they were quality tires and the car was aligned properly.
quote:I think examination of the Explorer/Firestone matter should give you a well-reasoned answer on that issue.
Originally posted by Jonny Z: A set of tires, inflated at the maximum allowed PSI on the sidewall (e.g. 44PSI), is less likely to blow out during high speed driving on a hot day, vs. a set of tires, inflated at a lower, vehicle manufacturer recommended pressure(e.g. 35 PSI). Same load condition is assumed.
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