Guest Author - William Charles Vetter

How do you know how much air to put in a tire? If you can’t answer this question then please read on…

I was sitting in my car at a gas station recently waiting to use the air station to put air in my tires; there was a chill in the air so I knew that my tire pressure was probably too low. There in front of me was a woman using the air hose I waited patiently for her to finish. She was working on one tire for what seemed like an inordinately long time. I decided that she might be in need of some help. I got out of my car and asked her if I could help her. She looked up at me rather calmly and asked, “How do you know when it’s full?” My first instinct was to laugh, but I just smiled and helped her out. The answer to her question is at the end of this article.

There is a well-known advertising slogan by Michelin tires, “there’s a lot riding on your tires”. It’s a great slogan and it is very true, your life and possibly even the lives of your entire family are riding on 4 small patches of rubber! It’s not much when you consider what is at stake. Safety is always paramount and secondly there is always economy. In this series of tire articles I would like to help you to understand how a tire works and how they are constructed so that you can motor around safely and save money at the same time. These articles are not a multi-part series and can be read to provide knowledge as stand alone articles. You can skip the technical jargon if that bores you.

A tire is always “full” of air but the profile of a tire is designed to work best at a certain shape. That shape is at its optimum when the tire is inflated to a proper pressure. That perfect profile is also dependent on the weight of the vehicle above the tire. Therefore the proper inflation pressure cannot be known by the tire’s manufacturer simply because they don’t know your vehicles weight. Most people will tell you the proper inflation pressure is on the tire, which is not true! The proper inflation pressure is printed on a sticker that is affixed on the beam, which you can see when the driver side door is open. Your tire’s actual inflation pressure may need to be modified but for safety’s sake it should never exceed the maximum pressure which is printed on the tire’s sidewall.

TIP 1: Run your tires at the maximum pressure as printed on the tire’s sidewall to increase fuel economy, please note also that ride comfort may suffer as a result of a stiffer tire.

TIP 2: Run your tires at lowered pressure if you get stuck or are about to drive on a soft surface like sand, increasing the size of your tires footprint will allow your car to float somewhat and get better traction. Re inflate immediately when returning to paved roads. DO NOT operate under inflated tires at high speeds for prolonged periods. The heat buildup from excess sidewall flexing can cause delaminating and result in catastrophic tire failure, which may lead to accident, injury or even death!