Physical force applied over an area. Frequently referring to the force that compressed air exerts on the interior of a vehicle's tires and expressed in units such as pounds per square inch (psi) or Newtons per square meter (1 Pascal).
Questions tagged [pressure]
84 questions
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Low-side and high-side pressures lower than expected after AC repair
I just did my first automotive AC repair, after the compressor in my 2004 Lancer 2.0 ate itself, cracked its casing, and blew all the refrigerant out.
I think I did the repair & recharge correctly-- and the AC is blowing very cold-- but I'm…
Cognitive Hazard
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Why nitrogen and not carbon dioxide is used in critical tire applications?
In critical applications tires are inflated using pure nitrogen (link).
But carbon dioxide (CO2) is a larger molecule (will leak slower from the tire), as well as inert (will not oxidize rim and will not combust in case of an accident). (link)
Also,…
Sparkler
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Checking Tire Pressure when the tire is warm or cold
Witnessed a recent debate about what is the appropriate temperature to check tire pressure at. The debate centered around warm or cold, there wasn't an exact temperature given by any of the parties.
What is the appropriate time to take your tire…
DucatiKiller
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Should I fill my tire?
I measured the PSI on my rear driver tire (using a gauge pin - push it into the needle and a stick pops out with a reading), and I got a reading of 22 PSI. My tires are supposed to be anywhere from 30-34 PSI. The thing is, the rear driver tire (the…
semore_1267
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Should the inflation pressure for low profile tires be the same as for regular tires?
I always thought that even if you go the large wheel + low profile tire route one should keep the pressure to what's recommended by the manufacturer. However I noticed that some people swear by increasing the pressure significantly when they switch…
I have no idea what I'm doing
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How does tire pressure affect susceptility to hydroplane?
Is a tire's propensity to hydroplane proportional or inversely proportional to tire pressure? That is, if a tire is over inflated or under inflated, is it more or less likely to hydroplane?Edit: This subject came up in this thread and the…
BillDOe
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Tyre Valve Pin Too Far In
I just bought a second-hand car, and when I got it home I tried to check the tyre pressures, with a simple mechanical pressure gauge like this, which I've used for years on previous cars with no issue.
It was fine for 3 of the 4 tyres, but I…
DaveyDaveDave
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Radial tires: Do they bulge at too high pressure?
It's tire pressure time! At least when looking at the recent new questions.
So here is another question about air pressure.
At driving schools, shops and in the internet you often find this type of images:
The left tire has the correct pressure,…
sweber
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How critical is it to match the stock fuel pressure regulator pressure when replacing it?
My fuel pressure regulator needs replacing, however the original part from the manufacturer is outrageously expensive. While looking for less financially painful alternatives I've seen much cheaper universal units or similar units made for other…
I have no idea what I'm doing
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Why is it that when supercharging, it's preferred to compress the input, rather than pull a vacuum on the exhaust?
It's a strange dilemma, but if the power of an engine is determined by the difference in pressure between the combustion chamber and the exhaust, it should follow that turbocharging should be equally effective pumping air out the exhaust, than in…
tuskiomi
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Direct Injection Injectors - How do they prevent blow back into the fuel system?
So I imagine a direct injection injector as a fuel injector squirting fuel directly into the combustion chamber. The amount of pressure in the combustion chamber would seem to be enough to push the fuel back into the injector.
Obviously that is not…
DucatiKiller
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Does free revving a diesel engine to 4000 rpm (1.6 crdi- hyundai) cause any damage?
It's a Hyundai CRETA/ ix25 model... clocked 1800kms on the odometer, diesel spec engine 1.6 crdi unit, manual transmission! It has redline at about 4800rpm in the tachometer. When i took it for service! the idiotic mechanic FREE REVVED the engine…
Vivek S
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Why does a tire have the same air pressure when mounted on the car and when not?
The other day I inflated my tires up to 34psi and then when I took one of them off the car. I measured the pressure again to check how much the difference was, and I was surprised that it was still 34 psi.
What I suppose is that when the tire is…
Pablo Matias Gomez
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How To Pump Up Car Tires (finding the optimal PSI for your tires)
I have noticed that all the tires on my VW Passat B5 have "44 PSI" written on them except the spare that has "51 PSI". This seems incredibly high to me so when I filled them up recently at the petrol station I put them all on about 35-38 PSI for…
Max Goodridge
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Does high air pressure throw off wheel balance?
The tire shop balanced my tires at 41 psi, when my recommended psi is 30. I have since lowered it to specification, but would this throw off the balance?
nachos
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