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Post by the light works on Apr 12, 2015 14:40:14 GMT
myths about shooting out tires and delaminating tires decapitating people have already been done, but there have been several minimyths in the old boards about tires.
those I recall: overinflating tires: better gas mileage, worse traction, worse treadlife.
should tires be inflated to the pressure posted on the sidewall?
a car will always have the same contact patch regardless of the size of tires you install?
you can generally go as fast as your tire pressure in standing water without hydroplaning
I don't know if anyone has ever addressed the old practice of always keeping radial tires on the same side of the car when rotating. I know some performance tires have a directional tread, but was there any basis to that rule? would it make for good TV, anyway?
any ideas for making these into a show idea, or any more tire minimyths?
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Post by sracing on Apr 12, 2015 20:49:54 GMT
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Post by the light works on Apr 12, 2015 21:59:03 GMT
exhibit A: over time my right front tire ebbed to about 70#. I noticed it because it tended to not hold corners as well on left turns, and when I checked the tread profile, it was starting to wear more on the shoulders. back up to full pressure, and it's holding good, again.
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Post by the light works on Apr 12, 2015 22:11:22 GMT
lifted from the funny picture thread: do tires conduct electricity or not, and if they have a dielectric quality, what is the breakdown voltage?
its out of range for a standard meter, and I can't justify getting a megger for that.
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Post by c64 on Apr 13, 2015 14:57:17 GMT
According to the BGR (German Federal Institute for Geosciences and Natural Resources), car tires must have a resistance lower than 10E08 Ohm (BGR 132) to avoid explosions during refueling. I doubt that the actual resistanve is much lower than that or our feds would not bother. So even at 380kV (maximum over here), the power inside the tires is not that much (~150W). As soon as the arc is burning, the voltage over the rubber is rather low anyway. according to the closest I could find to a breakdown voltage, clean rubber has a breakdown voltage of 20KV/CM. - so wyou have about 20KV to get to the steel belting and another 20 to get to the ground. You Americans sure love your low profile tires! When my car came out, the tires it came with were unusual wide and low profile for EU standards. And they still have about 10 centimeters between the edge of the rim and ground. And if a lightning strike or HV feeder line has the choice between rubber and air, it will pick air since even dry air is between 10kV and 15kV per centimeter. |
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Post by GTCGreg on Apr 13, 2015 15:52:47 GMT
You Americans sure love your low profile tires! When my car came out, the tires it came with were unusual wide and low profile for EU standards. And they still have about 10 centimeters between the edge of the rim and ground. And if a lightning strike or HV feeder line has the choice between rubber and air, it will pick air since even dry air is between 10kV and 15kV per centimeter. Not all Americans love them. This American thinks they're stupid. Hit one small pothole (and those we do seem to love at least based on numbers) and the rim is shot. |
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Post by Lokifan on Apr 13, 2015 16:52:21 GMT
You Americans sure love your low profile tires! When my car came out, the tires it came with were unusual wide and low profile for EU standards. And they still have about 10 centimeters between the edge of the rim and ground. And if a lightning strike or HV feeder line has the choice between rubber and air, it will pick air since even dry air is between 10kV and 15kV per centimeter. Not all Americans love them. This American thinks they're stupid. Hit one small pothole (and those we do seem to love at least based on numbers) and the rim is shot. Ditto. And I always thought it was a BMW affectation. Who did start using those silly things? |
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Post by c64 on Apr 13, 2015 23:51:33 GMT
Not all Americans love them. This American thinks they're stupid. Hit one small pothole (and those we do seem to love at least based on numbers) and the rim is shot. Ditto. And I always thought it was a BMW affectation. Who did start using those silly things? I think it was Daimler. And then Goodyear invented inflatable tires. |
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Post by the light works on Apr 14, 2015 4:19:36 GMT
according to the closest I could find to a breakdown voltage, clean rubber has a breakdown voltage of 20KV/CM. - so wyou have about 20KV to get to the steel belting and another 20 to get to the ground. You Americans sure love your low profile tires! When my car came out, the tires it came with were unusual wide and low profile for EU standards. And they still have about 10 centimeters between the edge of the rim and ground. And if a lightning strike or HV feeder line has the choice between rubber and air, it will pick air since even dry air is between 10kV and 15kV per centimeter. you don't have steel belting in your tires? I think my truck tires are only an inch thick, and they are the heaviest tires that fit the wheels. |
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Post by c64 on Apr 14, 2015 19:44:48 GMT
You Americans sure love your low profile tires! When my car came out, the tires it came with were unusual wide and low profile for EU standards. And they still have about 10 centimeters between the edge of the rim and ground. And if a lightning strike or HV feeder line has the choice between rubber and air, it will pick air since even dry air is between 10kV and 15kV per centimeter. you don't have steel belting in your tires? I think my truck tires are only an inch thick, and they are the heaviest tires that fit the wheels. So your truck is equipped with solid rubber wheels? Mine have ~ 8 cm of air in between and ~ 10cm tall side walls. |
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Post by the light works on Apr 14, 2015 20:02:27 GMT
you don't have steel belting in your tires? I think my truck tires are only an inch thick, and they are the heaviest tires that fit the wheels. So your truck is equipped with solid rubber wheels? Mine have ~ 8 cm of air in between and ~ 10cm tall side walls. no, it's not. the rubber has multiple layers of steel belting sandwiched in the middle of it, to increase the strength of the rubber. steel, of course, being so conductive that the US still allows it to be used for grounding electrodes.  |
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Post by c64 on Apr 14, 2015 21:22:13 GMT
So your truck is equipped with solid rubber wheels? Mine have ~ 8 cm of air in between and ~ 10cm tall side walls. no, it's not. the rubber has multiple layers of steel belting sandwiched in the middle of it, to increase the strength of the rubber. steel, of course, being so conductive that the US still allows it to be used for grounding electrodes. Well, that explains a lot. Those "diagonal" tires are obsolete since the 1970s over here. They are still around because they have advantages on mud so <25kph vehicles may still have them. Such tires rated for more than 150kph vanished in the 80s. I wouldn't dare to put those on my car, they can break pretty soon on fast vehicles so they are highly dangerous! Big rigs and especially construction machinery (all rather slow) are similar built but use kevlar instead of steel for the sides. All cars over here use radial tires since the late 70s. They usually have steel but none in the sides them self. Mine are kevelar, the only steel is in the lip which connects to the rim. They are much more expensive but more stable in hard turns and they are lighter. |
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Post by c64 on Apr 14, 2015 21:50:02 GMT
Here is a picturr of a common (EU) tire de.m.wikipedia.org/w/index.php?title=Datei:Radial_Tire_(Structure).svg&lang=deSteel is drawn in blue. My favourite kind of tire I use since 1998 is the same but uses kevlar belts instead of steel belts. Everybody sais that it doesn't make any difference so I just waste money. But the handling of the car feels better. Could be other factors of my favourite brand but I don't care. I like them and had no tire failure ever since. I had blown my share of diagonals with farming equippment and broke two radial steel belts on my first car within a few years until I switched to kevlar. They are 40% more expensive but I belief they are worth it! |
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Post by the light works on Apr 15, 2015 1:37:27 GMT
no, it's not. the rubber has multiple layers of steel belting sandwiched in the middle of it, to increase the strength of the rubber. steel, of course, being so conductive that the US still allows it to be used for grounding electrodes. Well, that explains a lot. Those "diagonal" tires are obsolete since the 1970s over here. They are still around because they have advantages on mud so <25kph vehicles may still have them. Such tires rated for more than 150kph vanished in the 80s. I wouldn't dare to put those on my car, they can break pretty soon on fast vehicles so they are highly dangerous! Big rigs and especially construction machinery (all rather slow) are similar built but use kevlar instead of steel for the sides. All cars over here use radial tires since the late 70s. They usually have steel but none in the sides them self. Mine are kevelar, the only steel is in the lip which connects to the rim. They are much more expensive but more stable in hard turns and they are lighter. that IS a radial. I keep forgetting that a ton GVW vehicle is heavy where you are, so you can get away with light duty tires. the only thing we use bias tires on any more is bicycles and lawnmowers - and the heavier ones of those use radials because they are so much better on soft terrain. keep in mind, each ONE of my tires carries the entire weight of your car. |
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Post by the light works on Apr 15, 2015 1:49:29 GMT
Here is a picturr of a common (EU) tire de.m.wikipedia.org/w/index.php?title=Datei:Radial_Tire_(Structure).svg&lang=deSteel is drawn in blue. My favourite kind of tire I use since 1998 is the same but uses kevlar belts instead of steel belts. Everybody sais that it doesn't make any difference so I just waste money. But the handling of the car feels better. Could be other factors of my favourite brand but I don't care. I like them and had no tire failure ever since. I had blown my share of diagonals with farming equippment and broke two radial steel belts on my first car within a few years until I switched to kevlar. They are 40% more expensive but I belief they are worth it! an here is a picture of a common fire truck tire: selector.goodyeartrucktires.com/cfmx/web/truckblank/img/cutaways/g395_cut-and-text.jpgI've blown three sets of radials on the work van I drove for the last company I worked for. my truck just ground off the tread until I started buying real truck tires for it. |
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Post by silverdragon on Apr 15, 2015 5:53:46 GMT
EDIT..... This post has been copied over to the thread citadelofmyths.freeforums.net/thread/1489/collected-tire-myths that TLW has already started in Transportation myths do not answer it here....One thing I cant get used to is split rims. I think we almost outlawed them here in UK many years back as being bloody dangerous. Now all tyres are tubeless single piece wheel one piece tyre and a big machine to hammer them over the rim. (Ok, its a lever, but you get what I mean?...) There was a thing that you should never put cross-ply and radial on the same axle. I have seen why.... I know why... As Cross-ply is almost extinct, I am wondering, is it worth re-trying that as a myth, to show "the youngsters" how bloody useless cross-ply was?... Does anyone still use cross-ply tyres?.. If so, why, .... and where...... Just as an indication. Cross-Ply.
The two side by side.
Undressed.....
Radial construction.
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Post by silverdragon on Apr 15, 2015 5:59:34 GMT
EDIT..... This post has been copied over from picture board.There was a thing that you should never put cross-ply and radial on the same axle. I have seen why.... I know why... As Cross-ply is almost extinct, I am wondering, is it worth re-trying that as a myth, to show "the youngsters" how bloody useless cross-ply was?... Does anyone still use cross-ply tyres?.. If so, why, .... and where...... Just as an indication. Cross-Ply.
The two side by side.
Undressed.....
Radial construction.
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Post by silverdragon on Apr 15, 2015 6:03:25 GMT
Cross-ply vs Radial.
Now I was told they have different grip at different speeds.
And that was why they were no good on the same axle.
Never did find out which was which...
As in which has better grip at slower, which is better at faster etc...
I am beginning to wonder if that in its self isnt an actual myth, and that as Cross-Ply has become almost extinct, that Radial were just better tyres "back then" and that they have evolved even further now.
I am wondering if...
If, if you had developed Cross-ply further, would they have been better eventually than Radial.
Its the old VHS vs Betamax question...
And for the record, Betamax was better.
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Post by silverdragon on Apr 15, 2015 6:19:53 GMT
Tyres and Sparks.
Well, they are rubber....
And rubber is an insulator.
First question, what is the official description of Insulator to be used when asking this question...
[From here on in, I am talking in quotes a lot, because these quotes are how most of us understand this subject, and how the few of us should investigate "what we know" to investigate this myth, so anything I "quote" is up for discussion, as it may just well be a misconception that we all take for granted?... ]
Second question when does that *Not apply*.
Third, obviously, *Compared to what*
In answering the second, I have to wonder just how many products can be used to show that they insulate *Up to* a certain amount of sparks...
Where that amount is the triangle of V=I/R, is it the current or voltage that breaks the insulation "rating" and starts to become conductive.
Compared to what...
We know a Faraday cage will keep you safe.
So what else?...
Would standing inside a "plastic" cage keep you safe?...
And how thick would it need to be?...
At what stage would the sparks be strong enough to think the surface of a plastic cage is better than air?...
Has anyone on reading this far started to get the idea I am proposing they go talk to their friendly Van-De-Graph Generator friends and go borrow that lighting creating investigation facility again?....
At what point would we consider that stuff what they say, the only safe place in a lighting storm is hidden in the cupboard under the stairs with your Duvet over you head.
Put your head between your knees
And close you eyes
Then you can kiss
Your (A**h*le) goodbye...
(Fallout calypso, Mike Harding.)
The thing with that fire truck hitting an overhead power line that shorted out and set its tyres on fire.
Just what would have prevented that being a problem.
Bigger thick rubber sheet underneath the appliance?...
Better road insulation rating? (the tarmac..)
So does the type of ground you are on change things.
Is a big sheet of concrete flooring or roadway an insulator?....
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Post by c64 on Apr 15, 2015 10:46:55 GMT
I have seen arcs jumping from thr rim to ground hugging the rubber when someone knocked over a light pole with a harvester. This was right after the accident when the breaker tried to reset. doesn't mean the rubber isn't also carrying a substantial current. but I just opened a tire thread, maybe this should get added. wood is also conductive at those voltages. Not just at those voltages, that's how moisture detectors for firewood work. The probe voltage usually is 6V or less. Even the driest wood I can find in the attic has some reading and those beam are in a dry place for over 100 years! Of course there is some power released directly inside the rubber. They must have less than a Gigaohm (according to standards) but a few hundred Watt won't give you instant fire. |
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