Is Driving on the beach harmful to the undercarriage?

[Nakk]

The missing part of physics that you are ignoring is the fact that inflation is not the only part of the tire that carries weight. You can roll tires along the ground with zero inflation. So clearly, there is something going on other than the pressure inside the tire. It's not zero.

Wow, you need to work on your reading comprehension. Both the original post you replied to and the latest one both mention and account for load carried by the sidewall. Try reading both posts again really carefully, LOL. And yes, once the tire is flat, assuming it's not a run flat tire, the load is now carried by the rim of the wheel and whatever small force would be carried by the sidewall in that situation.

 

[gnuarm]

Wow, you need to work on your reading comprehension. Both the original post you replied to and the latest one both mention and account for load carried by the sidewall. Try reading both posts again really carefully, LOL. And yes, once the tire is flat, assuming it's not a run flat tire, the load is now carried by the rim of the wheel and whatever small force would be carried by the sidewall in that situation.

The problem is you keep talking about the contact patch as being a constant. That's why I asked about the added area when in sand, yet you failed to understand the question.

contact patch is EXACTLY 60 square inches

I'm not interested in a pissing contest with you. If you aren't interested in discussing this rationally, I think we are better off not bothering.

 

[Nakk]

The problem is you keep talking about the contact patch as being a constant. That's why I asked about the added area when in sand, yet you failed to understand the question.

I'm not interested in a pissing contest with you. If you aren't interested in discussing this rationally, I think we are better off not bothering.

No, I didn't fail to understand the question, you failed to read my posts, or were incapable of comprehending basic sentence structure. Both of my posts mentioned--and accounted for--sidewall load. You claimed they did not account for the fact that there was another factor besides tire pressure. You're right, we can't have a rational discussion if you can't read and comprehend posts.

The fact is, we can safely ignore sidewall load--unless we're running run flat tires--as the load our sidewalls carry is negligible as a percentage of the total. Run flat tires and "E" rated tires have sufficient sidewall strength to invalidate our basic contact patch equation enough to matter.

There's no "magic" happening in sand that increases the contact patch. Try really hard to read and understand this: The tire is flexible. It has a given tire pressure. If the tire pressure exceeds the load one square inch of sand can hold, the tire will flex out until the tire runs into resistance stretching out. In other words it becomes round and is held in place by the sidewall. At this point, it is no longer carrying a load. The portion of the tire carrying the load is the portion of the tire that is flat against sand. That portion will adjust until the pressure from below is equal and opposite to the pressure in the tire. If the two forces are not equal and opposite, the tire will accelerate in the direction of applied force. (for instance when your car is bouncing.) Since your car isn't floating above the sand, you know with absolute certainty that the pressure applied by the sand is exactly equal and opposite to the pressure in the tire. Hence, contact patch = weight/(air pressure - sidewall load)--assuming the tire pressure isn't so low that you're running on the rims.

I'm not the one being irrational. You're just making up crap and upset that physics says you're wrong.

 

[gnuarm]

No, I didn't fail to understand the question, you failed to read my posts, or were incapable of comprehending basic sentence structure. Both of my posts mentioned--and accounted for--sidewall load. You claimed they did not account for the fact that there was another factor besides tire pressure. You're right, we can't have a rational discussion if you can't read and comprehend posts.

The fact is, we can safely ignore sidewall load--unless we're running run flat tires--as the load our sidewalls carry is negligible as a percentage of the total. Run flat tires and "E" rated tires have sufficient sidewall strength to invalidate our basic contact patch equation enough to matter.

There's no "magic" happening in sand that increases the contact patch. Try really hard to read and understand this: The tire is flexible. It has a given tire pressure. If the tire pressure exceeds the load one square inch of sand can hold, the tire will flex out until the tire runs into resistance stretching out. In other words it becomes round and is held in place by the sidewall. At this point, it is no longer carrying a load. The portion of the tire carrying the load is the portion of the tire that is flat against sand. That portion will adjust until the pressure from below is equal and opposite to the pressure in the tire. If the two forces are not equal and opposite, the tire will accelerate in the direction of applied force. (for instance when your car is bouncing.) Since your car isn't floating above the sand, you know with absolute certainty that the pressure applied by the sand is exactly equal and opposite to the pressure in the tire. Hence, contact patch = weight/(air pressure - sidewall load)--assuming the tire pressure isn't so low that you're running on the rims.

I'm not the one being irrational. You're just making up crap and upset that physics says you're wrong.

Not sure why you needed bold. Are you yelling???

I'm sorry that you can't understand that a tire in sand has a larger contact area than on a solid surface. That's why it takes so much more work to cross the sand in a car, and why it is easier to get stuck. The wheels sink in, and are always trying to climb out of the hole.

This is a simple fact. Enjoy.