? For people with ATV tires

[NoleFan4Ever]

Hey Sergio quit reading my mind....

[ag4ever]

Hate to be the bearer of bad news, but the pressure inside the tire is exactly the same as the pressure exerted on the ground. The contact patch will grow in size under less pressure in the tire and shrink with more pressure in the tire.

Contrary to popular belief, the cart does not ride on the sidewalls of the tire, it actually rides on the air in the tire. The tire is just a vessel designed to contain that air.

There is a reason air pressure is measured in pounds per square inch, not pounds per cubic inch.

[Sergio]

ag4ever, I don't think we are on the same page...

If You have a 1 ton car and a 2 ton car using 30PSI tires, the pressure per square inch exerted on the ground (Load) is not 30PSI is it?

The 30PSI inside the tire is not what is putting pressure on the ground, the weight of the car in LBs above the tires divided by the area (square inches) of the ground contact is what determines the PSI on the ground.

I think You are applying a different meaning to PSI as we are in this case.

[NoleFan4Ever]

Originally Posted by Sergio

ag4ever, I don't think we are on the same page...

If You have a 1 ton car and a 2 ton car using 30PSI tires, the pressure per square inch exerted on the ground (Load) is not 30PSI is it?

The 30PSI inside the tire is not what is putting pressure on the ground, the weight of the car in LBs above the tires divided by the area (square inches) of the ground contact is what determines the PSI on the ground.

I think You are applying a different meaning to PSI as we are in this case.

Totally agree....

And ag4ever not trying to team up on you, but as Sergio just explained, the relationship we are referring to is a different relationship. Another scenario is when you are riding down the road with a 10" wide tire (PSI in the tire is irrelevant for this point but lets just say it is 30psi) on a 2500 pound car and when you go thru the water puddle there is not enough down force to keep the tires in contact with the road and it hydroplanes. Now, run the same test again with the same 10" wide tires (and 30psi) on a 3500 pound car and when you run thru the same puddle it does not hydroplane. It was due to the down force applied by the increased weight of the car applying more pounds per square inch onto the road through those same tires...

[ag4ever]

Originally Posted by Sergio

If You have a 1 ton car and a 2 ton car using 30PSI tires, the pressure per square inch exerted on the ground (Load) is not 30PSI is it?

Yes, correct. It is 30 PSI.

The 1 ton car will have 1/2 the size contact patch as the 2 ton car.

Both cars will exert 30 PSI on the ground (roughly).

Physics: equal and opposite reactions.

(This all assumes the sidewalls carry no load. Depending on the tire construction they can carry no load or significant load. If we are talking typical car tires, they carry an insignificant load.)

[ag4ever]

Originally Posted by NoleFan4Ever

Totally agree....

And ag4ever not trying to team up on you, but as Sergio just explained, the relationship we are referring to is a different relationship. Another scenario is when you are riding down the road with a 10" wide tire (PSI in the tire is irrelevant for this point but lets just say it is 30psi) on a 2500 pound car and when you go thru the water puddle there is not enough down force to keep the tires in contact with the road and it hydroplanes. Now, run the same test again with the same 10" wide tires (and 30psi) on a 3500 pound car and when you run thru the same puddle it does not hydroplane. It was due to the down force applied by the increased weight of the car applying more pounds per square inch onto the road through those same tires...

Might want to do some research or experimentation to prove your hypothesis.

Unless we are talking about solid rubber tires or tires with extremely stiff and non-compliant sidewalls, the pressure in the tire is what holds the vehicle up. If it did not and it was the tire that held the vehicle up you would not need air in it.

[NoleFan4Ever]

Originally Posted by ag4ever

Might want to do some research or experimentation to prove your hypothesis.

Unless we are talking about solid rubber tires or tires with extremely stiff and non-compliant sidewalls, the pressure in the tire is what holds the vehicle up. If it did not and it was the tire that held the vehicle up you would not need air in it.

Lol... Not worth debating - If you feel you know it, then by all means you run with it. Hypothesis are easy when there is empirical data supporting them but hey, it is like my old grandpappy use to say, you can lead a horse to water but you cannot make him drink. I cannot tell you what to do or not to do as your perception is your reality. That is the case with all of us....

[dundeebarnbuggy]

Yes ag is right. the psi in the tire equals the psi on the ground plus around 5 psi for the tire carcass stiffness. Skinny tires have less square inches touching the ground and need more air pressure compared to a wide tire to carry the load. Thus they tend to push the tread into the soil more creating better steering in most conditions. On asphalt the tire grips by friction alone, [no penetration], so a larger tire will have a larger contact patch and tend to grip better.

[ag4ever]

Originally Posted by ag4ever

The contact patch will grow in size under less pressure in the tire and shrink with more pressure in the tire.

Let me fix this...

The contact patch will grow in size under less pressure in the tire and shrink with more pressure in the tire, if the load on the tire remains the same.

The contact patch will increase in size if the load on the tire is increased and decrease if the load on the tire is decreased, if the pressure in the tire remains the same.

[NoleFan4Ever]

Originally Posted by ag4ever

Let me fix this...

The contact patch will grow in size under less pressure in the tire and shrink with more pressure in the tire, if the load on the tire remains the same.

The contact patch will increase in size if the load on the tire is increased and decrease if the load on the tire is decreased, if the pressure in the tire remains the same.

That I agree with you on and we are both on the same page there.... Where you are referring to "load" I am with "weight".