My Costco has fancy outdoor tire pumps for usage by customers that have a severe over-inflation issue. These have a fancy interface for setting the tire pressure, and will even decrease the pressure in an over-inflated tire.
Here is the problem I observed. The customer was watching a tire inflate, and the connector was allowing air to escape (hissing). A Costco employee came and said that the pump would not work correctly with the hissing. When the connection was improved the unit showed that the tire had been inflated to 65 psi. The employee said just leave it connected, and it would automatically deflate the tire, which it did. Clearly, there are major safety issues here. Would such an over-inflation ruin a tire?
I should add that the customer had some difficulty getting the connector to properly seal, so this scenario is likely to be a common occurrence.
Also, the instructions on the unit said that you should stand away from both the tire and the hose during inflation. They did not warn of the hissing hose issue. I think I will stick with my hand-held gauge.
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Overinflation will destroy the tire. The machine is trying to be foolproof. The world continues to make bigger fools.
Edit… It will ruin the tire if driven at high pressure. It can damage the tire, depending on the tire, just over inflating it.
When the TPMS light comes on, some people just keep adding air trying to get the light off. Many cars won’t turn it off until you drive the car…So the driver WAY over inflates the tire in the process. On another forum, I have seen pictures of tires set to 60, 80 and even 100 psi.
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Sure would!
Tester
Totally agree, a very over inflated tire can be unsafe… Not to mention it will turn the tire into a basket ball… lol
Remember the pressure readings on the dash boards are not 100% marks, but tire psi’s… 
I don’t understand your last sentence. What dashboard?
Some cars, as mine does, provide the actual tire pressure of each tire. The dash readout matches when I manually check the pressures. Can watch the pressures increase as you drive the car, mine; 32 PSI cold, ~36 PSI when driven. Whereas my older truck just warns of a tire being low.
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All of this is academic if you just have your own compressor. And usually the dash figures are fairly close to what I get with the tire gauge. Watching new tires being put on though, I think they run the pressure way up getting the beads to pop. Just momentarily thought. I suppose one has exploded on someone someplace though.
I wonder how a leaky connection between pump and valve stem would cause over- pressure? You’d think it would cause under-pressure. When I’m checking the inflation of my bicycle tires
with a pencil-type gadget, sometimes a leaky connection will cause the reading to be higher than it actually is. Maybe the explanation is related to that same effect.
Never used something like that but I would think it would keep pumping air in and never get a shut off reading.
Back to car polishing, I bought a new pack of touch up paint after my old dried up. One scratch that has been bothering me so I touched it up. Very unsatisfied with the gray match. Little later looked again and had used primer. The correct one was a perfect match. All animals are equal. Some are more equal than others and read labels.
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Sometimes I get better visual results on a small scratch by not trying to match the paint, just covering it with clear paint.
I think if you imagine a hose with air at 80 psi connected to a tire with 20 psi that a whole lot of air will be going in, even if the connection has a small leak that is enough to hiss. The rates of flow are a lot different from the days we would hand pump a bicycle tire and had a bad connection.
My best 12 volt electric pump is small and slow, but the hose has a screw connection and threads on just like the cap does, so leaks are not a problem. The gauge shows the progress, and it even goes up to the 60 psi needed for that mini spare.
The threaded connector would solve Costco’s liability problem.
Even though a small amount of air keeps going into the tire, the pressure sensor at the pump reads lower due to the leak around it. So it keeps pumping despite the tire pressure continuing to rise above the threshold. This is a major failing of the pump design to account for this scenario. It should stop occasionally and measure the pressure. If it sees a drop in pressure happening without the dump valve enabled, it should stop and warn the operator to check the connection.
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The pressure sensor is at the pump and it reads the pressure in the hose. No matter how much you try to theorize this, the pressure in the tire cannot keep going up past the pressure in the hose. Period, end of story. The story told by the OP is bogus.
The automated tire inflators on our machines; Hunter tire balancer for example, pause every 10 to 15 seconds to read the tire pressure, then resume to complete inflating the tire to the desired pressure. A leak at the coupler would cause the inflator to continue inflating beyond the target pressure, don’t leave the equipment unattended.
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I believe that what Twin Turbo has forgotten is the Bernoulli principle. He describes static air, when the actual problem arose due to moving air. As Nevada_545 notes, the Hunter units will pause and will stop the flow so that static pressures are measured accurately.
Picture the actual pressure gauge as mounted on a tee off the main hose.The air flowing past the tee will reduce the pressure in the gauge because the air is moving. These are the same forces that lift airplanes.
My apologies to TwinTurbo, It was “keith” who failed to take into account the effect of moving air on the pressure gauge. Keith’s statement is only true for static, non-flowing air. Since the Costco case had hissing, there was obvious air flow. And the 65 psi (static measurement) when the hose was disconnected indicates that the flow was significant.
The Bernoulli principle only increases the volume of air, not the pressure. It does decrease pressure in a certain zone but not increase it. The Bernoulli principle does not apply here anyway because it is a leak, not an airfoil.
Note: Air does not flow from low pressure to high pressure.
One quick way of describing the Bernoulli effect is that a moving stream of air has a reduced pressure. When this air moves past the tee connecting to the gauge, it pulls air out of the gauge. If you go to YouTube, you can see simple demonstrations, such as at Visualizing Bernoulli's Principle Experiment at Home | Science Experiments at Home | #YTShorts - YouTube
The whole reason a scientist gets his name attached to this is because it is a surprising, counterintuitive effect.