New Asphalt Driveway - How Soon to Drive Tractor over it?

[ruffdog]

Consider Newtons third law. For every action there is an equal and opposite reaction. Therefore if you have 35psi of air in your front tires, the maximum pressure per square inch applied to the asphalt is 35psi. Now that pressure is applied over many square inches. That is why the tire patch increases as you add weight to the loader. If you have a 3500# load on the front axle no square inch of the front tire will exceed 35psi.

What if half of the tire surface is air space (the space between the tread lugs)? Wouldn't the tread lugs be able to press into the ground with more than 35psi? (The exact amount would depend on the stiffness of the tire belting)

 

[orezok]

Cool. I'll let half the air out of my tires and the tractor will weigh half as much

Nope. The contact patch just gets twice as big.

 

[orezok]

What if half of the tire surface is air space (the space between the tread lugs)? Wouldn't the tread lugs be able to press into the ground with more than 35psi? (The exact amount would depend on the stiffness of the tire belting)

The contact patch will expand depending upon the actual contact area of the tire. Void spaces are not counted. Now if you have foam filled tires the whole dynamics changes.

 

[radios1]

I just had my street done with asphalt, and traffic was on it the same day, without any problems!.. I couldn't imagine having to not use the street for a week!:shocked:

 

[Peter 315]

when we pave at work the cars drive right over it and sometimes the guy driving the dump truck also....

 

[chim]

Nope. The contact patch just gets twice as big.

I'll admit to daydreaming when I should have been paying attention in school, so rather than refer to Newtonian principles, I'll try another route - only because there may be some impressionable kids reading. Like the ones who believed the grade school teacher who said the centrifugal force of the earth spinning was the only thing that prevented gravity from pasting them to the ground. That was a teacher of mine and she did really say that. I was a compliant little fellow who wouldn't dare question something even that ridiculous out loud. Figured she had that wrong though because Eskimos and penguins at the poles somehow managed to remain erect while "standing on the ends of the axle".

Using your theory, I can remove a tire/wheel from my tractor, remove the valve stem to reduce the air pressure to zero. Then stand the tire on my driveway and since there is no air pressure inside, there's no weight on the driveway at all. Maybe it'll float away like a helium balloon?

Then I inflate the tire to 35 PSI and all of a sudden it applies 35 pounds per square inch to the driveway although there would be no measurable increase in its weight.

Next, without changing the inflation pressure I put it on the tractor and park the 5,000# tractor on the driveway and it still applies 35 pounds per square inch pressure to the driveway.

 

[Buppies]

I believe the paver made his recommendation based on your region other areas have different rules based on type of soil compaction even asphalt mixes. It would be hard for me to comment on as your local conditions are not known. Virginia would be entirely different than yours. I would follow my installers recommendations
Very nice job by the way

 

[s219]

Using your theory, I can remove a tire/wheel from my tractor, remove the valve stem to reduce the air pressure to zero. Then stand the tire on my driveway and since there is no air pressure inside, there's no weight on the driveway at all. Maybe it'll float away like a helium balloon?

Then I inflate the tire to 35 PSI and all of a sudden it applies 35 pounds per square inch to the driveway although there would be no measurable increase in its weight.

Next, without changing the inflation pressure I put it on the tractor and park the 5,000# tractor on the driveway and it still applies 35 pounds per square inch pressure to the driveway.

I hope you are joking with these questions, can't really tell. Think of the air in the tire like a spring that can do stuff within an intended range of operation. For the tire the range would be from a minimum pressure where the air lifts the rim off the ground and the tire won't roll off the rim, to a maximum pressure based on the max PSI the manufacturer puts on the sidewall (probably to prevent a blowout). In between those extremes the contact area and the tire pressure will vary inversely so that area x pressure = weight.

Let me go back to the spring analogy and apply your line of questions. Picture a spring on some farm implement.

"If I took the spring off and threw it down a giant hole would it still work on my implement?" Answer is no.

"If I bottom out the spring so I'm now metal on metal will it still work?" Answer is no.

"If I stretch the spring past the point where the metal can return to the original shape and it looks like a pretzel, will it work?" Answer is no.

"If I use the spring within it's normal operating range, will force always be proportional to length of the spring past neutral?" Answer is yes!

 

[coldsteelva]

Am I crazy? Or is the air pressure IN a tire only a measure of how much force the air INSIDE the tire is exerting on the interior surfaces of said tire?

 

[s219]

Am I crazy? Or is the air pressure IN a tire only a measure of how much force the air INSIDE the tire is exerting on the interior surfaces of said tire?

Since the only thing separating the bottom of the tire from the rim is the air, that same air pressure over the contact area is what supports the vertical load pressing down on the tire. For loads, you just need to think about the air pressure on the parts of the tire that support the weight.