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Post by alabastersandman on Dec 2, 2014 6:33:54 GMT
What other good reason is there? Good being defined as not busted by the MB's Distraction. Even without people do the most stupidest things at gas stations. E.g. forget to pay or spilling gas. I forgot to pay for my gas one night, it was only like $5 but still. I noticed once I got home that I still had the $5 so I drove back to the gas station to pay them. It was only 2.6 miles away and when I got there the cops were there, I asked them if they were looking for me? They said "if you just drove off without paying for your gas we are" I told them yep. Your looking for me, I thought I'd come pay the guy so you can stop looking for me. They acknowledged that they figured I legitimately had forgotten and not stole it. After all, not many people will risk stealing gas and not fill up. |
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Post by alabastersandman on Dec 2, 2014 6:53:03 GMT
A small diameter/long hose will slow down the flow of air but will not affect the pressure
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Post by c64 on Dec 2, 2014 23:46:01 GMT
A small diameter/long hose will slow down the flow of air but will not affect the pressure Exactly. But people think that the pump steals the amount of air which fits into the hose. And they can "proof" it by reconnecting the hose which shows that the pressure is lower than was dialled in. Those people simply can't understand that the system does steal air from the tire but then instantly returns this air by pumping so the pressure in the tire is correct. They belief that the hose could steal the air AFTER pumping and during disconnection. The hiss from the air escaping the hose confirms their misunderstanding. |
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Post by wvengineer on Dec 3, 2014 0:33:37 GMT
A week or so ago, I was driving my car out of town and the low pressure warning light came on. I stopped at the first gas station I could find with free air and they had one of those automatic stations. It was 10F, so I didn't want to fumble with a tire gauge.
I noticed that this one worked in spurts. The compressor would run for a few seconds and then stop to evaluate pressure. A few seconds later It would start up again and repeat as needed to get up to pressure. So that one at least took pressure readings with everything at static pressure. At static, the readings will be the same at the compressor as the tire.
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Post by GTCGreg on Dec 3, 2014 15:13:19 GMT
A week or so ago, I was driving my car out of town and the low pressure warning light came on. I stopped at the first gas station I could find with free air and they had one of those automatic stations. It was 10F, so I didn't want to fumble with a tire gauge. I noticed that this one worked in spurts. The compressor would run for a few seconds and then stop to evaluate pressure. A few seconds later It would start up again and repeat as needed to get up to pressure. So that one at least took pressure readings with everything at static pressure. At static, the readings will be the same at the compressor as the tire. I still don't trust the calibration of any of these self-serve air stations. That's why I keep a gauge that I trust in each car and always use it when filling the tires. Most of the self-serve stations are OK but I have found some to be off by a considerable amount. They're not like gas pumps that have to be periodically checked. I'm sure most air stations are never checked for accuracy. |
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Post by c64 on Dec 3, 2014 15:28:50 GMT
A week or so ago, I was driving my car out of town and the low pressure warning light came on. I stopped at the first gas station I could find with free air and they had one of those automatic stations. It was 10F, so I didn't want to fumble with a tire gauge. I noticed that this one worked in spurts. The compressor would run for a few seconds and then stop to evaluate pressure. A few seconds later It would start up again and repeat as needed to get up to pressure. So that one at least took pressure readings with everything at static pressure. At static, the readings will be the same at the compressor as the tire. Correct. That's how all of them work. Some fill with a fixed timing of the valve in e.g. ~1PSI intervals until the pressure is close enough, others check the pressure, add a second of air, then calculate how fast the tire would be inflated to the correct pressure and then inflate the tire in long intervals just to check if the guess is still correct to prevent overinflation. The problem is that when people connect a long hose, the reading is lower since air escapes from the tire into the hose until its pressurized. The compressor would return the lost air from connecting the hose so the air pressure is correct after disconnecting. But when disconnecting, people hear the his of the decompressing hose and think this is the moment when the air is lost out of the tire. When they reconnect and the hose really steals the air (but silently) they see the lower reading and think this confirms their fear that the tire pressure is lower than was dialed in after disconnecting. Just a while ago after adding more pressure to my tires for maximum payload, I had told the next guy to be careful and check the setting. My car is designed to handle a ton in payload and needs a rather high pressure (2.8 and 3.0 bar) when maxed out. His car was a bit smaller and there was no way that this car could handle any significant payload and it was empty. So I had asked him if he is really sure about this. Of course he was. 2.5 was the biggest number he could find in the table (I assume this is for the emergency wheel or something), some more to save fuel and then even more because the hose steals. |
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Post by c64 on Dec 3, 2014 15:50:51 GMT
A week or so ago, I was driving my car out of town and the low pressure warning light came on. I stopped at the first gas station I could find with free air and they had one of those automatic stations. It was 10F, so I didn't want to fumble with a tire gauge. I noticed that this one worked in spurts. The compressor would run for a few seconds and then stop to evaluate pressure. A few seconds later It would start up again and repeat as needed to get up to pressure. So that one at least took pressure readings with everything at static pressure. At static, the readings will be the same at the compressor as the tire. I still don't trust the calibration of any of these self-serve air stations. That's why I keep a gauge that I trust in each car and always use it when filling the tires. Most of the self-serve stations are OK but I have found some to be off by a considerable amount. They're not like gas pumps that have to be periodically checked. I'm sure most air stations are never checked for accuracy. Here in Germany, its different. There is a high penalty when the gauging office finds a decalibrated air pump. There's always a sticker on them when they were last calibrated and interval is rather small. Car repair shops may not even have an uncalibrated air gauge in their workshop area. But you are correct, don't trust the tables and readings. Experiment how much you really need and use the same gauge every time (local fuel station). It depends on the tire and its condition how much you really need. But never vary too much from the manufacturer recommendations. For my current summer tires, 0.2 bar extra is good because this still won't affect the wear pattern, saves fuel but still doesn't affect the braking distance. This was good for all summer tires I owned for this kind of car as far as I can remember. The ones which came with my previous car were bad anyway no matter what I did so I gave them to a friend for his classic car to sit on during the winter. The ones I bought next had maximum traction at +0.1 bar which had to be increased to +0.3 bar during degrading. The current ones are best with -0.1 bar. The ones my car had come with were soo good that the local Kindergarten now owns a set of tire swings |
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Post by the light works on Dec 3, 2014 16:17:22 GMT
my truck tires inflate to 5.5 bar
the difference between your air stations and the air stations I am used to over here is that ours have a check valve at the tire fitting, which holds the hose at full pressure between uses.
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Post by c64 on Dec 3, 2014 16:31:21 GMT
my truck tires inflate to 5.5 bar the difference between your air stations and the air stations I am used to over here is that ours have a check valve at the tire fitting, which holds the hose at full pressure between uses. I have a car, not a truck. It has a self-carrying unibody and (almost) independent suspension. It's not exactly rated for 1000kg payload but this is the maximum overload you can get away with. A bit more and the police will ground you because 1t of payload maxes out the tolerance of the police scale already. You just have to make sure the gas tank is ¼ full or less, then all you need to pay is €15 in penalty. Those automatic air columns are not that long around. They came up with them to prevent vandalism and theft. I liked the "classic" portable ones much better. Much more convenient to handle and highly reliable. Just make sure it hisses when picking it up and you know that it will work. The stationary ones might deflate your tire when defective and then you are as stationary as the pump.  |
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Post by the light works on Dec 3, 2014 16:43:34 GMT
my truck tires inflate to 5.5 bar the difference between your air stations and the air stations I am used to over here is that ours have a check valve at the tire fitting, which holds the hose at full pressure between uses. I have a car, not a truck. It has a self-carrying unibody and (almost) independent suspension. It's not exactly rated for 1000kg payload but this is the maximum overload you can get away with. A bit more and the police will ground you because 1t of payload maxes out the tolerance of the police scale already. You just have to make sure the gas tank is ¼ full or less, then all you need to pay is €15 in penalty. Those automatic air columns are not that long around. They came up with them to prevent vandalism and theft. I liked the "classic" portable ones much better. Much more convenient to handle and highly reliable. Just make sure it hisses when picking it up and you know that it will work. The stationary ones might deflate your tire when defective and then you are as stationary as the pump. but you can imagine how irritated I was when I checked my tire pressure after having my tires rotated at the tire center, and specifically making a point of telling them to be sure they were inflated to maximum pressure while they were doing it (you can't get to the fitting on the duals without removing them because of poor design) and then finding out they were only at 3.5 bar. gee, wonder why my tires are wearing so unevenly. I don't do business with that tire center any more. |
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Post by c64 on Dec 3, 2014 17:07:21 GMT
I have a car, not a truck. It has a self-carrying unibody and (almost) independent suspension. It's not exactly rated for 1000kg payload but this is the maximum overload you can get away with. A bit more and the police will ground you because 1t of payload maxes out the tolerance of the police scale already. You just have to make sure the gas tank is ¼ full or less, then all you need to pay is €15 in penalty. Those automatic air columns are not that long around. They came up with them to prevent vandalism and theft. I liked the "classic" portable ones much better. Much more convenient to handle and highly reliable. Just make sure it hisses when picking it up and you know that it will work. The stationary ones might deflate your tire when defective and then you are as stationary as the pump. but you can imagine how irritated I was when I checked my tire pressure after having my tires rotated at the tire center, and specifically making a point of telling them to be sure they were inflated to maximum pressure while they were doing it (you can't get to the fitting on the duals without removing them because of poor design) and then finding out they were only at 3.5 bar. gee, wonder why my tires are wearing so unevenly. I don't do business with that tire center any more. define maximum pressure. It can be the maximum their air gun was set to. |
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Post by the light works on Dec 3, 2014 17:36:45 GMT
but you can imagine how irritated I was when I checked my tire pressure after having my tires rotated at the tire center, and specifically making a point of telling them to be sure they were inflated to maximum pressure while they were doing it (you can't get to the fitting on the duals without removing them because of poor design) and then finding out they were only at 3.5 bar. gee, wonder why my tires are wearing so unevenly. I don't do business with that tire center any more. define maximum pressure. It can be the maximum their air gun was set to. the maximum rated pressure of the tire. edit: if your air line cannot fill a truck tire, then you have no business selling truck tires. |
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Post by the light works on Dec 8, 2014 19:30:20 GMT
here, a filling station with a pressure selector would most likely just have a regulator that only supplied air at the selected pressure. - so it would just go until the pressure was equal (and air stopped moving), even though it took three times as long.
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Post by silverdragon on Dec 15, 2014 8:55:11 GMT
I run with a digital tyre gauge... its pocket size and set to a certain calibration that will be no more than 0.5 lbs/sq inch out.
Truck tyres, I leave well alone... If I suspect the tyres may be low I get the mechanics to take a look.
As its difficult to get heavy goods tyres filled out in the wild, I make sure they are good before I leave.
Any problems out on the road, its a change of wheel time.
And I dont do that.
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