eli5: Why can you only learn your proper tire pressure from the car and not from the tires themselves. Wouldn’t different kinds of tires need different pressures on the same car?

Question

Same tires, different cars = different recommended tire pressure

Different tires, same car = same recommended tire pressure

This doesn’t make sense to me. Why is this?

In: Engineering

Answer 1

Optimal tire pressure is not a static setting! The total weight of the car includes all passengers and cargo. The difference between 1 driver vs +3 or 4 passengers and 7 days of luggage can mean 1000 lb difference! You’re supposed to increase and decrease tire pressure as the weight of the loaded car changes