I have a road cylcle/mt bike hybrid. How much air do I want keep in the tires? Do I need to use an air pressure gauge or should they just be filled to firm.
The ture usually has a psi level on it and you should use a pressure gage to fill it up to that level
check your sidewalls. the recomended psi will be there. use a floor pump with a guage on it, available at any bike shop. good pumps will have an arrow that you can position at your desired psi. when the needle hits the arrow, you're good to go. no reading tiny numbers! get a pump with a dual chuck (works with schrader or presta valves).
Use a guage...most hand pumps have them. The surest way to flat is to have your tires under-inflated. One good bump on an underinflated tire causes the tube to bottom out and pinch on the rim, giving you two small holes where the two sides of the rim cut the tube. This is known as (obviously) a pinch flat or a snakebite.
The tire sidewall has minimum and maximum pressures listed. On an MTB you sometimes bring the pressure down to the minimum for better traction in rain and other bad weather, but most of the time (especially in the city and commuting) you want to stay as close to the max as you can. In addition preventing flats, you'll feel the lower rolling resistance make it easier to pedal.
Look on the tire's sidewall. It will always have the max tire pressure. Unless you are slogging through mud or loose dirt, unlikely on a hybrid, you should inflate the tire to the max pressure. That will not only reduce the chance of flats, it will also minimize rolling resistance.
no firm could be out rated because i used to do that and can't tell you how many tires i pop blow up or flats i had heres what you do you first go to wal-mart or a bike shop and get you a tire pump with a gauge on it they are like $10 then you go and look on the side wall of your tires some left some right there will be a a psi max rateing on it don't put no more than that in it or you might pop the tire for ex only my bike right side MAX PSI 90 so hope this helps