HOW TO: Properly inflate your car's tires

It seems like common sense!  The tire looks a little flat, so you go to the gas station and put some air in it.  That's all there is to it, right?  Well - sort of.  A tire can lose nearly half of its recommended pressure and still look properly inflated.  That's why it's important to check tire pressure at least once a month.  And while many of us grew up with dad whipping out the chrome cylindrical gauge - the one with the little tape measure thing that pops out when fitted to the tire - experts recommend more accurate digital gauges.  So you go to the auto parts store and get one of the those - so now what?  How do I know what the tire pressure is supposed to be?  Many people look at the tire itself - which is wrong!  The value on the tire is the maximum pressure it can safely handle - which typically is significantly higher than what is recommended for your particular car.

 

Every car manufacturer posts proper pressure values somewhere on the vehicle.  Typically, a plaque like the one pictured above is located near the driver's door - either on the door itself, or in the door jamb.  You are looking for the "cold tire inflation pressure", and there should be numeric values for the front and rear tires - measured in PSI (Pounds [of air pressure] per Square Inch).  Now, it says "cold" because the pressure inside the tire changes as the temperature goes up and down.  An accurate reading, or "cold" reading, is taken before the car has been driven, or within a few miles of driving.  In other words, driving to the local gas station to use its air machine is fine, but checking pressure right after a trip down the thruway is not the time to do it.

Once you've determined what the pressure should be, and have found the need to add air after taking the cold pressure readings of all four tires - you're ready to pump some air.  Simply inflate your tire until the gauge shows it's where it should be.  And don't forget to check your spare once in a while.  As your set of tires age, there may be one or two that will lose air faster than the others.  I've now had this problem with two cars - which is why I've become quite experienced on this whole topic.  It's important to recognize when this is happening, so you can be extra careful to check those particular tires - perhaps each time you fill up the gas tank.  Eventually, you may want to consider having your mechanic try replacing the valve stem.  I did this, and also purchased a small portable air pump that plugs into a car cigarette lighter.  It cost less than $30 and prevents the hassle waiting in line for air at the gas station.

Regardless of what specific steps are taken to keep your tires properly inflated, it's important that you do it.  Not doing so not only means reduced gas mileage, but greatly increases the risk of an accident.  Over-inflating your tires reduces the amount of tread hitting the road - meaning worse handling, and making it harder to stop (especially on wet roads).  Under-inflating tires means too much of the tire tread is in contact with the road, which creates increased friction and heat.  This can lead to tire blowout and tread separation - either of which can cause a vehicle rollover.