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Finding the Correct Air Pressure

Air Lift air springs (also called air bags) are designed to help correct a number of different problems that occur as a result of carrying heavy loads with your vehicle. Different kinds of loads create different kinds of problems.

For example, the load of a slide-in camper for pick-ups not only causes your truck to sag, but it can also create roll from a higher center of gravity. The major benefit of Air Lift air springs is they can be fine-tuned to erase an array of problems. With the addition of an Air Lift on-board air compressor system, the adjustment can be made with the touch of a button.

A common question we receive is, “how much air should I put in the air springs?” Determining the proper air pressure is something that only you and your passengers can do and it comes down to three things: level vehicle, ride comfort, and stability.

1. Level Vehicle

Front-to-back and left-to-right, a level vehicle is safer, feels better, and handles better. This is achieved by returning an un-level vehicle to normal ride height. The most precise way to do this is to take measurements at each wheel well of the vehicle when the vehicle is unloaded (measure from the center hub to the bottom of the wheel well). Then, when the vehicle is loaded, adjust the pressure in the air springs until you can achieve similar measurements. An easier, yet less precise, method is to adjust the air pressure until your headlights are aimed where they are supposed to be.

2. Ride Comfort

Adjusting the air pressure up or down will change the ride quality of your vehicle, but determining which way to adjust is sometimes the question. A characteristic such as a harsh ride can be the result of either too much pressure or not enough pressure.

A bouncy vehicle is usually the result of weak suspension. The rate of the bounce is something we call natural frequency. The human body is more comfortable at a higher natural frequency than a lower natural frequency. Weak suspensions will create a lower natural frequency. For example: a pickup truck with a load of sand. A weak suspension would cause the vehicle to bounce slow and deep because the load is too heavy for the suspension. If this is the case you want to increase the air pressure in your air springs (therefore increasing the spring rate of the air springs).

If you removed all the sand from the pickup truck and now the vehicle bounces fast and shallow, the suspension may be creating too high of a natural frequency where it is uncomfortable. Try decreasing the pressure in the air springs.

3. Stability

Stability translates into safety and should be your priority, even when there may be a sacrifice in the previous two areas. Stability is usually attained by eliminating roll, bounce, diving during braking, and “sponginess.” Changing the air pressure in your air springs can easily tune out these problems and their presence is usually a result of too little air pressure in the air springs.

The Rules of Thumb:

  • Start with the vehicle level or slightly above.
  • If you have a motorhome, start with 90 – 100 PSI in the rear.
  • If the front of your vehicle dives while braking, add air to the front air bags.
  • If you ever suspect that your air bags have bottomed out, add air.
  • Adjust your pressure up and down to find the best ride.
  • If your vehicle “rocks and rolls”, add air.
  • If your vehicle bounces slow and deep, add air.
  • When in doubt, add air.

NOTE: It is very common to require different pressures in one side compared to the other. Loads such as water, fuel, appliances, etc. will cause the vehicle to be heavier on one side. As much as 50 PSI difference is not uncommon, but always consider your load. If it is an uneven load, you will probably need uneven pressures. If you have a motorhome, start by adding 100 PSI. At this point, your initial set up is complete and you are ready for your first drive with a load.

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