Tire Pressure Basics

Maintaining correct tire pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability, and performance designed to match the needs of their vehicles. Tire deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tire inflation pressure also stabilizes the tire’s structure, blending the tire’s responsiveness, traction and handling.

Tire Pressure Basics

A car is a weight-bearing machine.  A tire rated for inflation to 32 psi but only carrying 24 psi loses 10 percent of its handling capability on sharp turns. Every time you move the controls, you are shifting weight throughout the vehicle.  These shifts are all eventually felt at the tires.  The tires’ ability to bear that weight is dependent on the tire pressures.

Tire PressureActually, tires don’t support the weight of your car. It is the air pressure inside the tire that supports the car. The tire is basically a rubber container that holds the air the car rides on. Setting the correct tire pressure is required for good handling, traction and durability.

Here is where the problem begins, you can’t just set it and forget it. Road conditions and temperatures play a big role in the tires performance, and safety For every 10 degrees Fahrenheit change in ambient temperature, your tire’s inflation pressure will change by about 1 psi. It will go down with lower temps, and up with higher temps. The typical difference between summer and winter temperatures is about 50 degrees F. – which results in a loss of about 5-psi and will sacrifice handling, traction, durability, fun, and safety.

The Proper tire Pressure?

How can you determine the proper tire pressure? In a simple phrase “ It’s not easy”. Go by what the tire manufacturer recommends. The tire type, the load on the tire, and environmental conditions, determines the proper tire pressure. As mentioned above the condition that is literally deadly is low tire pressure combined with a heavy load on the tire.

The amount of weight you can support with a tire depends on the air in the tire. The more air in the tire the more weight the tire can support. The less air in the tire the less weight the tire can support. The max load is stamped on the side of the tire. The stamping will give a tire pressure number at a particular weight. As an example, “45 psi at 1450 Lbs”. The Tire Company is telling you that if you have 1450 Lbs on that tire you must have 44 psi in the tire. You can measure the tire pressure with a tire pressure gauge, but how do we determine the weight on the tire?

If you are not mathematically challenged, I suggest a simple procedure that can compute the weight on each tire.

Go to the owner’s manual and find the maximum weight the vehicle can accept. Also from the owners manual determine the weight distribution front to rear.

From that, you can compute the weight on each tire. Let’s take a hypothetical car that weights 4000 lbs. It has a weight distribution of 60/40. 60 % of that 4000 lbs. is on the front tires and 40 % of that weight is on the rear tires.

A quick calculation tells us that 2400 Lbs is on the front tires (4000 Lbs x 60%) and there is 1600 Lbs (4000 Lbs. X 40%) on the rear tires.

Another quick calculation will tell us that 1200 lbs. on each front tire (2400 / 2) and 800 lbs on each back tire (1600 / 2). Through the magic of math, we have determined that your car, loaded, has 1200 lbs on each front wheel, and 800 lbs on each back wheel.  Now go back to what is stamped on the side of the tire. If the stamping indicates 38 psi at 1200 lbs, you need to have 38 psi on those tires.

We recommend that you check tire pressure at a minimum of once a month. Once a week would be better. If you are responsible for company vehicles, supply the drivers with a tire pressure gauge. Don’t overload the vehicles. Know the load-carrying capacity of the vehicle, especially SUV’s and pick up trucks.