Is the X too heavy for a tile floor garage?

[ajdelange]

@cypho in post #13 already covered it:
"There is a limit to how much the tires can flatten out. If you let the pressure drop too low, the wheels will touch the ground and the PSI the floor sees will go through the roof ( since the wheels will not flatten at all).

All of a sudden you will have all 6000lbs pressing down over 0.5 sq inch of wheel for 12000psi onto the floor. That is when your tiles will crack."
What is your point?

The point is that what transfers the load depends on the relative elasticities and geometries of the load bearing elements. You evidently accept that when the air's elasticity goes to 0 all the load must be borne by the tyre's structural components. But you don't seem to be able to comprehend that the principal holds universally, not just at the extreme where all the air has been let out. Take your flat and add just enough air pressure to get the rim off the rubber. What have you got? A tire with a whole lot of really distorted rubber but no weight on the rim. Do you not understand that it takes force to distort rubber? Where do you think that force comes from? It is the weight of the car. Forces come in couples (Newton 3 I think) and so the rubber pushes back. The rubber is supporting the weight of the car. It is transferring the load of the car to the patch.

Rubber is at least approximately Hookian. That means that it takes more force to distort it a lot than a little. A badly distorted flat tyre is subject to and thus producing more counter force than a properly inflated one. Thus, our nearly flat tyre is producing more upward force than normally. Where would you say this force is going if not to hold the car up? At low tyre pressure the rubber carries more of the load than it does than at high. If you think the rubber carries no load, at all, at normal tire pressure then, if you follow the discussion above, you must think there is some threshold pressure at which the rubber switches off. Can you tell me what you think that pressure is?

Someone who has taken high school physics should be able to understand this.

 

[ajdelange]

The bottom of the patch is intimately adhered to the part of the tire subjected to the internal air pressure. The bottom of the patch therefore is subjected to the same air pressure. ....
The pressure inside the tire is 42PSI GREATER than the outside air. The pressure at the rubber patch in contact with the ground is 42PSI because it is one with the internal wall.

Please don't insult my intelligence.

You don't need any help from me on that. You are saying the pressure on then outside of my nitrogen bottle is 3000 psi because it is "intimately adhered" to the inside?

If that's really what you mean to say it is clear evidence that it would be a total waste of my time, and yours, to continue this discourse.

 

[teethdood]

The point is that what transfers the load depends on the relative elasticities and geometries of the load bearing elements. You evidently accept that when the air's elasticity goes to 0 all the load must be borne by the tyre's structural components. But you don't seem to be able to comprehend that the principal holds universally, not just at the extreme where all the air has been let out. Take your flat and add just enough air pressure to get the rim off the rubber. What have you got? A tire with a whole lot of really distorted rubber but no weight on the rim. Do you not understand that it takes force to distort rubber? Where do you think that force comes from? It is the weight of the car. Forces come in couples (Newton 3 I think) and so the rubber pushes back. The rubber is supporting the weight of the car. It is transferring the load of the car to the patch.

Rubber is at least approximately Hookian. That means that it takes more force to distort it a lot than a little. A badly distorted flat tyre is subject to and thus producing more counter force than a properly inflated one. Thus, our nearly flat tyre is producing more upward force than normally. Where would you say this force is going if not to hold the car up? At low tyre pressure the rubber carries more of the load than it does than at high. If you think the rubber carries no load, at all, at normal tire pressure then, if you follow the discussion above, you must think there is some threshold pressure at which the rubber switches off. Can you tell me what you think that pressure is?

Someone who has taken high school physics should be able to understand this.

Sigh...so it's down to using extremes where the rubber is forced to maintain its integrity not by using air pressure but by its material characteristics, and questioning whether I have a HS Physics grasp, to dispute the fact that the ground pressure is very close to the tire inflation pressure. Got it.

 

[mongo]

This is your first mistake. The internal pressure when the gauge reads 42 PSI is 57 PSIA. Where the tire is in contact with the air there is a force of 57 pounds on each square inch of the inside with a force if 15 lbs on the outside for a net of 42 pounds termed 42 PSIG with the G standing for "gauge" because that's what a gauge would measure. There is no air under the patch so the only force countering the air pressure from the outside of the patch is 1/4 the weight of the car divided by the patch area.

I think you are claiming that there is vacuum/ no void between the tire and the ground. If so, that is incorrect. If that were the case, you could attach a tire to the ceiling by pressing a sufficient contact patch. Traction would also be much better than it is and rolling losses would be horrendous. The tire does not seal to the ground.
If you did make a vacuum, then the tire would be exerting an additional force equal to the 14.7 psi pressing against the top of the tire of area equal to the contact patch in addition to the vehicle weight. As a visualization of your scenario, imagine resting a tire on the ground, the more contact area, the more down force from ambient air pressure, the more contact area, and so on until the tire is highly deformed at which point you could not lift it off the ground.

The rubber is supporting the weight of the car. It is transferring the load of the car to the patch.

In a tubeless tire, the sidewall between the rim and the top of the tire holds the car up. The top of the tire is held up by air pressure, the air pressure also acts against the ground (contact patch * air pressure) along with the sidewall load. The rubber in contact with the ground only serves to contain the air, it is not supporting anything (beyond sidewall effects at the edge).

 

[teethdood]

You don't need any help from me on that. You are saying the pressure on then outside of my nitrogen bottle is 3000 psi because it is "intimately adhered" to the inside?

If that's really what you mean to say it is clear evidence that it would be a total waste of my time, and yours, to continue this discourse.

One is inflatable by air, the other not. You know what I meant I suspect, but by throwing out an un-inflatable steel cylinder as an example... we're going to have to agree to disagree. I'm out.

 

[Darmie]

.we're going to have to agree to disagree. I'm out.

On a light note, your message count is going up.

 

[ajdelange]

I think you are claiming that there is vacuum/ no void between the tire and the ground.

No, I don't think I am saying that. What I am saying is that I cannot see how the atmosphere can exert an upward force on the patch if air does not contact the patch. I am not entirely comfortable with this and I certainly acknowledge that in a groove, for example, air does reach the interior of the patch and there certainly would be upward force within the groove. But if I do another gedanken experiment in which I push a hollow cylinder into a tank of water until it reaches the bottom and let go it will float and that has to be due to the water getting in under the bottom. The only way to prevent it from floating would be to insure that the water was excluded from reaching the bottom surface e.g, with a suction cup.

If so, that is incorrect. If that were the case, you could attach a tire to the ceiling by pressing a sufficient contact patch. Traction would also be much better than it is and rolling losses would be horrendous.

Suppose I have a piece of rubber lying on something very smooth (a piece of glass). The piece of rubber weighs 1 gram and has top (and bottom surface area 1 in^2). I have pressed the rubber against the glass hard enough to push out all the air. There is thus, a vacuum under the rubber. Now I want to raise this piece of rubber 1 meter. The forces acting down on it are 9.8*(14.7/2.2 + 1/1000) newtons. To get it to move up by dh I must do apply a wee bit more than 9.8*(14.7/2.2 + 1/1000) n force but only while dh is less than the width of an air molecule. Let's use 1 nm (about 12 nitrogen covalent radii). Once the piece has been moved that far air can rush in under and there is now and upward force of 14.7 lbs to balance out the downward force. The work required to "break" the vacuum would be 1E-9*9.8*(14.7/2.2) = 65 nJ. Thus I don't think rolling resistance would be much effected. As to sticking the tire to the ceiling..?

In a tubeless tire, the sidewall between the rim and the top of the tire holds the car up. The top of the tire is held up by air pressure, the air pressure also acts against the ground (contact patch * air pressure) along with the sidewall load. The rubber in contact with the ground only serves to contain the air, it is not supporting anything (beyond sidewall effects at the edge).

Trying to stand back a bit and see the forest I guess my position at this point is that rubber is Hookian and, therefore, if it is distorted it is loaded. The rubber is thus transferring load to the patch.

 

[mongo]

No, I don't think I am saying that. What I am saying is that I cannot see how the atmosphere can exert an upward force on the patch if air does not contact the patch. I am not entirely comfortable with this and I certainly acknowledge that in a groove, for example, air does reach the interior of the patch and there certainly would be upward force within the groove. But if I do another gedanken experiment in which I push a hollow cylinder into a tank of water until it reaches the bottom and let go it will float and that has to be due to the water getting in under the bottom. The only way to prevent it from floating would be to insure that the water was excluded from reaching the bottom surface e.g, with a suction cup.

There are at least a couple ways: trapped air and surface roughness, we're not talking planes of glass with water in between .

Your cylinder has no way to generate a vacuum unless it deforms upon contact with the bottom like a suction cup.

Suppose I have a piece of rubber lying on something very smooth (a piece of glass). The piece of rubber weighs 1 gram and has top (and bottom surface area 1 in^2). I have pressed the rubber against the glass hard enough to push out all the air. There is thus, a vacuum under the rubber. Now I want to raise this piece of rubber 1 meter. The forces acting down on it are 9.8*(14.7/2.2 + 1/1000) newtons. To get it to move up by dh I must do apply a wee bit more than 9.8*(14.7/2.2 + 1/1000) n force but only while dh is less than the width of an air molecule. Let's use 1 nm (about 12 nitrogen covalent radii). Once the piece has been moved that far air can rush in under and there is now and upward force of 14.7 lbs to balance out the downward force. The work required to "break" the vacuum would be 1E-9*9.8*(14.7/2.2) = 65 nJ. Thus I don't think rolling resistance would be much effected. As to sticking the tire to the ceiling..?

Does the air rush in, or is only that edge now experiencing atmospheric pressure? How does that work if you try lifting the tire? (opposite of gravity pulling the tire off the ceiling). If the tire surface were made of cups, and the surface was smooth enough, you could force out the air and then get additional contact force. Since the treat is a convex surface, this doesn't happen.

Trying to stand back a bit and see the forest I guess my position at this point is that rubber is Hookian and, therefore, if it is distorted it is loaded. The rubber is thus transferring load to the patch.

Yah, the sidewall will exert some force, but the majority is the internal air pressure. Check out top fuel dragsters for an extreme example of floppy sidewalls. They use the flexibility to add more final gear ratio by letting the tire balloon due to centripetal force.

 

[SaniDel]

Tangentially related. I have EpoxyShield and it does not like EVs whatsoever. Maybe it was not applied correctly, but 2 years of use with an Honda Civic and Mazda Tribute left no mark. First time I parked a 500e and i3 with wet tires and let them sit overnight, the paint underneath the contact area stuck to the tires and came right off. Same when I replaced the Fiat with a Model S.

Maybe it is not the weight but the tires themselves but, there it is...

Perhaps it was because the tires on the EVs were new?

Tires are made of rubber, but there are a lot of chemicals involved. Walk into a tire store ... notice the “new tire” smell? No idea what that is, but it may have softened the EpoxyShield on your garage floor so that it stuck to the new tires unlike the old tires on your ICE vehicles.

Also ... interesting that this happened the first time you parked your EVs with wet tires. I’ve heard “it never rains in Southern California” so could the “first-time wet” tires on your EVs have tracked something from the recently-rained on roads into your garage? EpoxyShield is tough to remove!

One last possibility is heat. The rear tires on our ICE vehicle are often hot due to radiated heat from the exhaust system ... significantly hotter than the front tires. As a result ... the TraxTile is more discolored under the rear tires than the front tires. Without an exhaust system an EV wouldn’t have this problem, but how about the heat from the battery?

 

[Vinc]

Perhaps it was because the tires on the EVs were new?

Tires are made of rubber, but there are a lot of chemicals involved. Walk into a tire store ... notice the “new tire” smell? No idea what that is, but it may have softened the EpoxyShield on your garage floor so that it stuck to the new tires unlike the old tires on your ICE vehicles.

Also ... interesting that this happened the first time you parked your EVs with wet tires. I’ve heard “it never rains in Southern California” so could the “first-time wet” tires on your EVs have tracked something from the recently-rained on roads into your garage? EpoxyShield is tough to remove!

One last possibility is heat. The rear tires on our ICE vehicle are often hot due to radiated heat from the exhaust system ... significantly hotter than the front tires. As a result ... the TraxTile is more discolored under the rear tires than the front tires. Without an exhaust system an EV wouldn’t have this problem, but how about the heat from the battery?

Very good observations. I did not think about it this way, but it is true that the ICE cars that I had before already had somewhat used tires after we first painted the floor, not brand new.

Probably is a sum of all of the above, chemicals from the new tires plus rain mixed with road whatevers. And without much knowledge, I would also speculate that the low rolling resistance compound perhaps is also a factor... For some reason it seems that the Fiat 500e would stick to the floor much worse than the i3.

 

[SSonnentag]

To answer the original question, the weight of the vehicle will not crack your tile. However, concrete (almost) ALWAYS cracks due to settling. Earthquakes can greatly accelerate settling. If the floor/concrete develops any imperfections, the tile will break. So while the X won't directly cause the cracking, you will almost certainly get cracked tiles where your concrete cracks. Some of the flexible subfloor underlayments available may help prevent cracking though.