Say for example that my tires are supposed to be at 30psi according to the owners manual. The air in the tires can only be released, so wont the tires be under 30 in not too long unless i check every fews days or so? so the manual saying 30, does that mean that maybe the tires are best at 28-29? and do 30, to be safe according to the manual? or should i just do 30+ always. and i doesnt matter what the tire says, right?thanks
Not just permeatation as others have stated, but tires also change pressure due to the ambiant air temperatures. Still, loss of more than a pound or two per week indictes other problems, such as puncture or leaking stem. A properly inflated tire is best for safety and economy. Too much air lessens the footprint on the road, too little affects braking and steering and generates excess heat leading to shorter tire life. Also can use more fuel. Not all tires require the same air pressure. Check your vehiclle owner's manual or your tire dealer to be sure of what is correct.
Tires do leak down slowly over time but it should take over a month. If they leak down in a week or less you have a problem that can be fixed at a tire shop. Weather changes also affect tire pressure.air expands when hot and contracts when cold so they need rechecked after big temp changes. Technically they recommend running the tires at the pressures listed on your door sticker or owner's manual for best performance of the car. I usually air mine up to the highest recommended pressure on the tire itself. Not all of my cars have stock sized tires anyway.and with more air they have less rolling resistance and gas mileage might be slightly better.
If you look on the driver's door, you will find a sticker stating what the air pressure should be in the original equipment tires that came on the vehicle. If you have installed custom wheels and tires, this pressure could change and you should consult the shop that sold you the new tires for accurate information regarding pressure. The pressure listed on the sidewall of the tire is the tire manufacturer's maximum allowed pressure. This pressure reflects the maximum the tire can safely be operated at, not the pressure the auto manufacturer states (due to weight distribution, suspension, wheel size, etc.) for safe operation of the vehicle. If you check your tire pressure with a gauge, once a month, you will extend the life of your tires. An over inflated tire will wear faster in the center of the tread. An under-inflated tire will wear the edges of the tread. Obviously, neither is a safe way to operate the vehicle. You should also consider having the tires rotated every other oil change. It keeps them equal in wear, because in most cases, the front tires will wear faster due to cornering, especially on front wheel drive cars. I hope this helps
