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Is the X too heavy for a tile floor garage?

pereiks

Member
Sep 25, 2019
109
17
Sammamish, WA
There's no confusion. The PSI in the tire is the same PSI that's hitting the tile. The tire serves to hold the air in, that's all. The tile is being subjected to the same 42PSI (plus a negligible weight of the tire). The tire is deformed at 42PSI over an area (36 square inches) to counter 1/4 the weight of the 6000lb vehicle.

Let's say you stack another MX on top of your MX to make it 12K lbs and no air is added to the tire, so the tire pressure remains at 42PSI, the tire deforms under increased load to increase the contact area with the tile. The contact area is now:
12,000lbs / 4 tires = 3000lbs/tire
3000lbs / 42 PSI = 143 square inches
143 square inches over a 12-inch wide tire means a contact rectangle of 12inx12in. The tire has now deformed or flattened to 12inx12in in contacting the tile underneath it. The contact area is increased under increased load, but the actual PSI is still the same, 42PSI.

I actually agree with you and apologize :)
I got a bit confused but after reading a bit more into topic the math is correct for approximation.
 
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mattack4000

Active Member
Oct 1, 2017
2,323
899
CA
My tiles didn’t dent from the car parked on it. It did dent when I left it on the jack for the night on a flat removal
 

Tube Guy

Member
Jan 2, 2019
61
17
So Cal
My real questions are:

Do people have problems with porcelain tiles cracking or lifting?

Does Swisstrax or Racedeck start looking like um...plastic after 5 years?
 

teethdood

Member
Jan 30, 2017
392
524
Visalia, California
My real questions are:

Do people have problems with porcelain tiles cracking or lifting?

Does Swisstrax or Racedeck start looking like um...plastic after 5 years?

I took my time to post the reason and the math/physics in this thread to explain why there should not be any problems with your porcelain tiles unless they are made out of mud. In simple terms, the weight of the vehicle does not matter because the weight is spread out over an area by the flattened tires. The heavier the vehicle weight, the more the contact area made by the tires. It spreads the load out. My other posts went over the physics behind it. Vehicles on rubber tires put a lot less pressure per surface area than a refrigerator+food on four small wheels. So the tile-cracking potential of a heavier weight of a Model X is not so different than a normal much lighter vehicle. (Think about what PSI - pounds per square inch - means).

Now if you put your car onto a jack stand with a small contact area like @mattack4000 in post #22, the weight is now concentrated on a small area and so it is much more likely to crack. So don't put your small jack stand directly on porcelain tile.

It astounds me when people mark posts "Disagree" when they don't post the reason why they disagree.
 

mattack4000

Active Member
Oct 1, 2017
2,323
899
CA
Ignore my foot but this is my race deck after 4.5 years and 2.5 with a Tesla. It looks old and dirty but no damage except the jack damage and I have a lot of issue with the transition piece. I just drive my car straight on them instead of using the gentle slope
 

SaniDel

Member
Aug 30, 2019
75
20
Greenville, Delaware
Does Swisstrax or Racedeck start looking like um...plastic after 5 years?

The TraxTile in the appended photograph was installed in December 2014. Five years later it looks the same with one exception. Hot tires tend to discolor the lighter tiles where the vehicle is parked. Unfortunately, the pattern I chose has our vehicle parked on the light silver in the center ... when the garage is empty there are tire marks where it was parked.

We have our garage floor professionally cleaned annually. The process is similar to steam cleaning carpeting ... a truck mounted boiler injects steam and detergent under pressure followed by scrubbing with a floor polisher and finished by vacuuming. Anything other than the tire marks is dissolved and removed. I could easily replace the four discolored tiles, but the problem would recur ... perhaps before we sell!

If I had to do it over I would pattern the tiles differently so that darker tiles were under the tires, but otherwise I am pleased with the product. If "looking like plastic" is a problem there are alternative products that "look like rubber" ... would that be better?

IMG_0932.jpeg
 
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GWord

Member
Aug 18, 2016
567
861
Houston, TX
In my experience there hasn’t been an issue with our X or our S in our tiled garage. No cracking of the tiles. We did build up the transition into the garage with a grout ramp so that stress wouldn’t be applied to the leading edge of tile at the garage door. That was the spot I was most worried about. One item to note is that the tiles we chose, like most these days, had a printed pattern to make them look like stone. The tires appear to be wearing that pattern down a little bit. Hard to see from the picture but my guess is that over the course of a number of years it will become noticeable.

garage.jpg
 
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SaniDel

Member
Aug 30, 2019
75
20
Greenville, Delaware
Is the slight deformation of the tile pattern where the vehicle was supported on a jack?

SwissTrax claims a compressive strength of 5,120 PSI which likely exceeds the strength of the underlying concrete!

https://www.swisstrax.com/garage/

I once had to beat something ... not someone ... with an elastomeric deadblow hammer on my TraxTile.

Welcome to Sears.com

Mission accomplished with no damage to the tile, but probably not a good idea with a steel hammer.
 

mattack4000

Active Member
Oct 1, 2017
2,323
899
CA
Yeah I had jacked it up four times previously, but the one time I left it overnight it dented
 

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SaniDel

Member
Aug 30, 2019
75
20
Greenville, Delaware
Yeah I had jacked it up four times previously, but the one time I left it overnight it dented

This begs the question about what would have happened without the tile? If the compressive strength for the tile is 5,120 PSI which is more than typical concrete in residential applications ... would the jack have crushed the 'crete? We all know what happens when jacking on asphalt ... big dents!
 

pchan

Member
Jan 20, 2016
109
69
Boston, MA
I took my time to post the reason and the math/physics in this thread to explain why there should not be any problems with your porcelain tiles ....

I didn't mark disagree even though I don't agree with your math. :) It is a discussion. No one is right all the time. Anyone took the time to post, explains and help out others with good intention should be appreciated.

The PSI inside the tire is NOT the same as the PSI on the tile. However, the force exerted by the entire wheel to the tile and the force received by the tiles is obviously the same.

P=F/A ... let's look at A. The area of the tire internal surface area should be used to calculated the tire PSI, not the area of the contact point. The contact point of the tire to the tile should be used to calculated the tile PSI. So A is different.

For the force F, the force of the tire PSI is the force of air inside exerted on the internal tire wall. Not the weight of the car. It is the volume of the air. (U can skip to the 2nd last line of this paragraph if you agree. :D) It is like squeezing a ballon will not affect it's PSI as long as the ballon can expand (PV=K). F is the force created by the difference between air pressure inside and the outside atmospheric pressure. F or the PSI of the tire will increase with higher attitude due to lower atmospheric pressure, but ironically, not related to the weight of the car. The weight of the car will increase the F indirectly only if it decreases the volume of the tire (not the shape). That explains why the tire is 45 PSI when it is on or off the car (P1 or P2). With heavy load, it is true that the contact point will increase and makes the wheel looks smaller, but the tire side wall as well as the entire shape of the wheel will also expand to maintain the internal air volume constant up to certain limit. (P1V1=P2V2, if P1=P2, V1=V2) With extreme heavy weight when the tire cannot expand anymore to compensate for the volume, the PSI will increase. In other words, the elasticity of the tire material (summer tire vs winter tire vs sports tire) in combination of the weight of the car will affect the tire PSI. Not the car weight alone. Meanwhile, the F on the tiles is simply total weight of the car divided by 4 not affected by attitude or temperature. So, F is different.

If the F and A of the tire and tile PSI formula are different, their PSI cannot be the same. Going back to the original question: "Is the X too heavy for a tile floor garage?" ... I don't know ;)
 

teethdood

Member
Jan 30, 2017
392
524
Visalia, California
I didn't mark disagree even though I don't agree with your math. :) It is a discussion. No one is right all the time. Anyone took the time to post, explains and help out others with good intention should be appreciated.

The PSI inside the tire is NOT the same as the PSI on the tile. However, the force exerted by the entire wheel to the tile and the force received by the tiles is obviously the same.

P=F/A ... let's look at A. The area of the tire internal surface area should be used to calculated the tire PSI, not the area of the contact point. The contact point of the tire to the tile should be used to calculated the tile PSI. So A is different.

For the force F, the force of the tire PSI is the force of air inside exerted on the internal tire wall. Not the weight of the car. It is the volume of the air. (U can skip to the 2nd last line of this paragraph if you agree. :D) It is like squeezing a ballon will not affect it's PSI as long as the ballon can expand (PV=K). F is the force created by the difference between air pressure inside and the outside atmospheric pressure. F or the PSI of the tire will increase with higher attitude due to lower atmospheric pressure, but ironically, not related to the weight of the car. The weight of the car will increase the F indirectly only if it decreases the volume of the tire (not the shape). That explains why the tire is 45 PSI when it is on or off the car (P1 or P2). With heavy load, it is true that the contact point will increase and makes the wheel looks smaller, but the tire side wall as well as the entire shape of the wheel will also expand to maintain the internal air volume constant up to certain limit. (P1V1=P2V2, if P1=P2, V1=V2) With extreme heavy weight when the tire cannot expand anymore to compensate for the volume, the PSI will increase. In other words, the elasticity of the tire material (summer tire vs winter tire vs sports tire) in combination of the weight of the car will affect the tire PSI. Not the car weight alone. Meanwhile, the F on the tiles is simply total weight of the car divided by 4 not affected by attitude or temperature. So, F is different.

If the F and A of the tire and tile PSI formula are different, their PSI cannot be the same. Going back to the original question: "Is the X too heavy for a tile floor garage?" ... I don't know ;)

For the record, in post #2, I said "if I understand correctly..." I was very open to discussion and learn. You obviously took the time to contribute and I appreciate that, whereas flyby "disagrees" by non-contributors don't enlighten anyone one bit.

Let's discuss, as I want to learn from you.

Say you pump a perfectly round balloon up to 42PSI. Everywhere on the inside, the internal wall of the balloon is experiencing an outward pressure of internal air of 42PSI. Everywhere on the external wall of the balloon, it must also experience an inward pressure from the external air of 42PSI to maintain a static system. When placed on the ground, at the point of contact, the ground itself must exert a force equal to 42PSI perpendicular to the point of contact. Do you agree with this statement?

The tire is basically a very rigid balloon. The internal pressure must be met with the same external pressure, otherwise the tire (or balloon) will keep expanding until the pressures equalize. So the PSI internally and externally are of the same vector.

As to the area of contact, how else do you propose we calculate the area? The tire will flatten a certain amount (you are right, depending on the characteristics of the tire) to distribute the load onto the ground while maintaining the same PSI. I did my math above in the other posts.
How would you calculate the PSI/area of contact experienced by the ground? 6000lb vehicle, 4 tires, 42PSI each tire.
 

pchan

Member
Jan 20, 2016
109
69
Boston, MA
Say you pump a perfectly round balloon up to 42PSI. Everywhere on the inside, the internal wall of the balloon is experiencing an outward pressure of internal air of 42PSI. Everywhere on the external wall of the balloon, it must also experience an inward pressure from the external air of 42PSI to maintain a static system. When placed on the ground, at the point of contact, the ground itself must exert a force equal to 42PSI perpendicular to the point of contact. Do you agree with this statement?

No, that’s not true. First of all, even before the ballon touches the ground, the PSI outside and inside are not the same. The force is equal but the pressure is not. The external surface area is large than the internal surface area because of the thickness of the balloon. I know for ballon the thickness is neglect-able, but it’s important since for the tire which is much thicker, it will be a little bit more significant. P=F/A, if the F is the same but A is different so P is different. The thicker the balloon, the more different it will be because the outside area A is much more than the inside area A.

Secondly, when the balloon touches the ground, it is true that the ground must exert the same exact force perpendicular to the point of contact but it’s not 42PSI. It’s weight of the ballon in N or kg, not in PSI. The PSI of the ground is the weight of the ballon divided by the area of the contact point while the psi of the ballon is 42. Don’t forget there’s also air at the non contact point excerting force on the ballon to keep it in shape. If it’s in a vacuum, the balloon will expand.

To calculate the PSI of the ground, we just need to know of the weight of ballon and area of the point of contact which can be measured with applying paint on the ballon outside before it touches the ground then measure it. For the model X, you can spread the water on dry concrete around the tires then move the car away to measure those 4 spots. The weight and the contact area is all we need for the formula, and the PSI of the tire is irrelevant.

As far as rigid ballon that you mentioned, the extreme case would be a metal drum which is a very rigid ballon. Whether the metal ballon inside is vacuum or 1000PSI wouldn’t affect the PSI on the ground. ;)
 
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ajdelange

Active Member
Dec 10, 2018
1,077
540
Virginia/Quebec
Without reading the whole thread carefully it seems to me that what you all are missing is that part of the weight on each tire is supported by the sidewall - not the internal air pressure. Draw the freebody diagram of the patch in contact with the ground. Acting up on it is 1/4 (approximately) the weight of the vehicle. Acting down on it is the a force equal to the internal pressure times the area and two additional forces through the sidewalls.
 

teethdood

Member
Jan 30, 2017
392
524
Visalia, California
No, that’s not true. First of all, even before the ballon touches the ground, the PSI outside and inside are not the same. The force is equal but the pressure is not. The external surface area is large than the internal surface area because of the thickness of the balloon. I know for ballon the thickness is neglect-able, but it’s important since for the tire which is much thicker, it will be a little bit more significant. P=F/A, if the F is the same but A is different so P is different. The thicker the balloon, the more different it will be because the outside area A is much more than the inside area A.

Secondly, when the balloon touches the ground, it is true that the ground must exert the same exact force perpendicular to the point of contact but it’s not 42PSI. It’s weight of the ballon in N or kg, not in PSI. The PSI of the ground is the weight of the ballon divided by the area of the contact point while the psi of the ballon is 42. Don’t forget there’s also air at the non contact point excerting force on the ballon to keep it in shape. If it’s in a vacuum, the balloon will expand.

To calculate the PSI of the ground, we just need to know of the weight of ballon and area of the point of contact which can be measured with applying paint on the ballon outside before it touches the ground then measure it. For the model X, you can spread the water on dry concrete around the tires then move the car away to measure those 4 spots. The weight and the contact area is all we need for the formula, and the PSI of the tire is irrelevant.

As far as rigid ballon that you mentioned, the extreme case would be a metal drum which is a very rigid ballon. Whether the metal ballon inside is vacuum or 1000PSI wouldn’t affect the PSI on the ground. ;)

Ground pressure - Wikipedia
"The ground pressure for a pneumatic tire is roughly equal to its inflation pressure."

The PSI of the tire is relevant. It is roughly equal to the ground pressure. If you read my other posts, I explicitly put the weight of the tire in between parentheses to account for the slight difference.
 

teethdood

Member
Jan 30, 2017
392
524
Visalia, California
So if the ground pressure ~ tire inflation pressure:
P = F / A
42PSI = Weight of Vehicle / Area
That's what I've been doing. No need for paint etc to calculate the area.

Back to the op's original question, 42PSI isn't going to crack your tile.
 
Last edited:

MichaelP90DL

Active Member
Apr 19, 2019
1,549
1,552
Lancaster, CA
If this were a classroom and the students were arguing in person, I'd just kick back and enjoy the ruckus. You should have seen me struggle through high school algebra. One year I actually got a B in math. I'm 73 now and still have no idea how I pulled that off.
 
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mattack4000

Active Member
Oct 1, 2017
2,323
899
CA
This begs the question about what would have happened without the tile? If the compressive strength for the tile is 5,120 PSI which is more than typical concrete in residential applications ... would the jack have crushed the 'crete? We all know what happens when jacking on asphalt ... big dents!

I doubt it would dent, but anyway I don't know. My house was purchased new, the tiles have been on the floor since day 1. I have the Racedeck. I use them on my small deck and my front entrance as a welcome mat. They are not perfect, but they do serve their purpose. I guess I am suppose to take them out often to clean underneath
 

ajdelange

Active Member
Dec 10, 2018
1,077
540
Virginia/Quebec
And besides ignoring the part of the load taken up by the sidewalls you are all failing to recognize that your calculations should be done with psia, not psig. Where the tyre is sealed to the tile the atmosphere cannot exert its normal 1 bar of pressure.

The important thing is, of course, that the force exerted by each of the vehicle's tyres is about 1/4 of the weight of the car.
 

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