How do New & Used Tires Support a Car?
Even I’ve thought about this millions of times; I mean, a heavy car on 12″ Used Tires ? How does that happen?
It all deals with the pressure & the square inches of the Tire. Since there is an approximately 30 psi per square inch, there must be quite a few inches of contact patch to actually carry the weight of that car of yours. If there is more weight on the car or you decrease the pressure of the tire, that just means that you need more square inches of contact patch; therefore, the flat spot gets bigger than usual. 
When you’re tire is spinning (obviously), the contact patch has to move around the tire so that way, it can stay in contact with the road you’re driving on. Considering an underinflated tire needs to bend more to make contact with the road, it takes more strength & energy to push it down the road; which means it leads to more heat.
But you knew this already, right?
Learning something new everyday,
Mykalanne.
Tags: 12" Used Tires, TIre, Tires
