Oddly enough I think this is right.

The contact patch size is roughly the weight of the car divided by the tire PSI. A 4000 lb car will have a 133 square inch contact patch. If you then take the weight of the car and divide it by the contact patch size you end up back at 30 PSI.

Similarly a 4000 lb car with 40 psi…

Sure. Like fingers. Totally special accessories.

Not a clone exactly, but close. More like a half-twin, because the alleles you carry from your two parents would be randomly shuffled again when you self-fertilized, your offspring would be halfway between a regular sibling and an identical twin.