There should be a pressure recommendation on the tyre sidewall. That value or slightly lower would be proper inflation.
When a tire is properly inflated it will be level to the ground. Over inflated and the middle of the tire has the most pressure on the ground. Under inflated and the sides of the tire have the most pressure on the ground.
The same as a tire that has not been inflated.
No, other factors that limit the life of a tire are failure to keep it properly inflated, poor wheel alignment and "burning rubber".
You really can't tell the exact pressure. All striking the side will do it tell you that there is pressure in the tire and enough experience striking a tire that is properly inflated will give you an idea if it is close to correct.
Put air in the tires and keep them properly inflated. It is there for your safety!
At minimum: a jack, a lug wrench (for the lug nuts), and a spare tire inflated properly. Helpful but not requiredn: tire blocks, gloves, and a flashlight (depending on light conditions).
Any tire inflated with a gas (air or nitrogen ) is a pneumatic tire.
Any tire inflated with a gas (air or nitrogen ) is a pneumatic tire.
physical
As a bike, or any vehicle with inflated wheels roll forward, the tire gets deformed, kinda squashed out. Scrunching up the rübber takes energy, and the more scrunching the more energy it steals. With a properly inflated tire the folds and waves of the tire is quite small, so there's not a lot of power lost. But with a flat tire the folds and deformation is bigger, and so is the energy loss.
less inflated.
There is no simple answer. Tire life is affected by many factors. To make a tire last make sure your tires are balanced, rotated often, properly inflated, and the alignment of the vehicle is good,