When I first started as a mechanic most cars were well maintained by dad or the teenage boys or the older boys in the family. However, as the years passed, gas stations stopped being “service stations” where young boys (like me) or girls pumped the gas, checked your tyre air pressure, cleaned your windshield and other windows, and checked your oil and other engine fluids. Now that entire employment sector is gone, due to self-serve pumps and child labour laws. Nothing is free anymore and everyone is expected to check their tyre pressures themselves.
Most drivers today fuel up and drive till the fuel gets low, only stopping to fuel up again, never checking the tyres. For your safety and better mileage keep your tyres properly inflated. Purchase good tyres especially if you drive in hot deserts, if it is a 120 degree day the black asphalt road could be 180 or more degrees. Tyres can easily fail in these environments.
If you drive in areas of high temperatures, over 80 degrees such as the desert southwest and your tyres recommended maximum air pressure is 50 psi then inflate your tyres to 40 psi cold.
If the maximum air pressure says 35 psi in these hot areas then your tyres should be inflated to 28 psi cold. As you drive your tyres will heat up, the air pressure will increase, and usually a tyre inflated at 40 psi will increase to around 50 psi on a hot day.
One way to be certain is after driving ten or more miles in really hot weather, check your tyres air pressure. If the tyres air pressure exceeds the maximum stated on the sidewall then lower it to that maximum. This is not a pleasant job, but you should only have to do it once. The reason is if you consistently drive with over inflated tyres, they may delaminate while you are driving.
In cold weather or areas of consistent cold you can inflate your tyres to 10?% under maximum stated pressure. If you feel a thumping sensation or hear it you could have a tyre which is delaminating or has developed a bubble. Have your tyres checked. Even still many shops miss these problems; you must look at and feel the tyres.
How to check the tyre pressure?
The air pressure in the tyre is very important. With the correct pressure, the tyre will wear longer, carry the rider comfortably, and it will make turns and brake better. The proper pressure also reduces the number of flats that will occur.
Tyre manufacturer always recommends a maximum pressure for the tyre– this is marked on the side of the tyre. This pressure maximum is determined by marketing departments, legal departments, and testing. The attorneys want a low pressure in case of a defective tyre that could cause a blowout. Marketing people want a high number because consumers think the higher the pressure, the higher quality of the tyre.
It’s a good rule of thumb to not go over or under the manufacturer’s recommended air pressure. All the good tyres manufactured in Australia have the maximum tyre pressure stated on the sidewall of each tyre.
Selecting a tyre pump
Selection of the tyre pump depends on the valve of your tyre. More money doesn’t always mean it is better. Try out the pump and read the label. When the gauge is pressed onto the valve, a stick at the opposite end comes out telling you what the air pressure is in the tyre.
A dial gauge has a needle that gives the tyre pressure. This type is recommended for tubeless tyres. A digital tyre gauge operates the same as the other gauges. It will give a digital reading of the psi in the tyre.
Losing how much pressure is considered normal
Losing a half pound of tyre pressure a week is normal, any more than that is reason to watch that particular tyres pressure each week. Doing this you will know to look for possible nails, screws, or other objects which may have impaled your tyre. Hitting a curb or pothole can bend or crack a wheel, causing a leak. Or temporarily move the tyre bead breaking its seal with the wheels rim causing the loss of air pressure.
When should you measure the tyre pressure?
Tyre inflation pressures are always recommended for cold tyres, and that means you should check the tyres every morning before driving the car. When a car is driven the tyres get hotter. This causes the air inside them to grow. If you check the tyres immediately after driving, the readings are going to be at least several pounds above the normal.
How much should I fill?
Use a tyre inflator with an accurate gauge to check your tyres. Do not depend on the built-in gauge or on a gas station air hose or compressor (which is commonly very inaccurate). If you will keep on adding air till the bulge disappears, the tyre is going to be highly overinflated. Likewise, do not hold back until the tyre is nearly flat to add air. It’s almost impossible to tell the difference between a tyre that has 10psi of air from one that has 20 psi of air. Make use of a gauge to determine the pressure in tyres regularly.
NOTE: Tyre inflation pressure ought to be more or less equal side-to-side. A couple of pounds difference might be enough to cause a visible steering or brake pull.
My tyres say 50 psi maximum. (Pounds per square inch). If I keep them at 50 psi (hot) I average 20 miles per gallon on the highway. When I bought them, unknown to me the tyre buster put 32 psi in them, wondering what was wrong when I checked my fuel mileage and found the car was only averaging 15 miles per gallon. I immediately checked the tyre air pressure and found they were only inflated to 32psi. That was a huge twenty-five per cent drop in miles per gallon. This was a very dangerous situation, under inflated tyres cause accidents and deaths.
Besides wasting fuel, under inflated tyres tend to roll under around corners and cause your car to sway. You may feel a mushy, sluggish feeling; the tyres will flex too much causing overheating of the tyre which will cause premature wear at best.
Veeral Patel is a self-employed mechanic who currently liuves in Perth, Australia.