Scalar
Because the air inside the tire is under pressure. Gas always flows from a region of higher pressure to a region of lower pressure. As the pressure inside the tire is greater than the pressure outside, the air always comes out of the bicycle tyre.
If the tyre is inflated, yes. If it has been completely deflated, no.
a difference in pressure (differential pressure). For example putting air in a tire (I know its pneumatics and not hydraulics but it is the same concepts.) the air tank is holding 110 lbs of pressure and when you connect the hose to a tire with 25 lbs the air is going to flow from the tank to the tire. or from high pressure to low pressure.
i can effect the pressure and make gripping difficult
In ambient air, with a barometer. In a tire or tank, with a diaphragm gauge.
scalar
In the USA Tire pressure is measured in PSI (pounds per square inch) Most of the rest of the world measures it in KPA (kilo Pascal's)
Because the air inside the tire is under pressure. Gas always flows from a region of higher pressure to a region of lower pressure. As the pressure inside the tire is greater than the pressure outside, the air always comes out of the bicycle tyre.
If inside and outside same pressure that means there is no pressure. The added pressure is what blows the tire up like a balloon and holds the weight of the car up.
Air leaves a tire when the tire valve is open due to the pressure. The pressure outside of the tire is lower than the pressure inside the tire.
NO - there isn't a pressure sensor inside the spare
The tire will have a recommended psi printed on the tire, it is best to follow this recommendation. Check inside driver door for tire pressure information. Tire lists max pressure at max load. Mfg will set tire presure on sticker inside driver door.
Tyre pressure is caused by the air particles inside the tyre
inside drivers door there is a label that states correct tire pressure.
they hit the walls/side of the tyre and that builds pressure
The tire will have a recommended psi printed on the tire, it is best to follow this recommendation. Check inside driver door for tire pressure information. Tire lists max pressure at max load. Mfg will set tire presure on sticker inside driver door.
look on the tire itself and it will give you the tire pressure or look on the inside door panel of the drivers side it will be there also