Understanding Airing Down

Definition of Airing Down Airing down your tires simply means reducing each tire's air pressure (psi) to a level which promotes improved traction and provides for a smoother ride on rough or uneven surfaces.

Purpose of Airing Down

• To improve traction by increasing the tire's contact patch with the trail. The wider contact patch provides better grip and allows the tire to conform to varying terrains

• To provide for a smoother ride by absorbing the shock of impact experienced while driving over rough terrain
  

How to Air Down

Here are three basic ways to air down:

1) Old School - Manually deflate your tires via the valve stem and use a tire gauge to check the air pressure until the desired pressure is achieved. The down side of this method is that it takes a very long time and you can only do one tire at a time.

2) Tire Deflators - To use the tire deflators you screw the pre-calibrated (you need to perform this step in advance) deflator on to the valve stem of each tire and the deflators will automatically reduce the tire pressure to the preset psi and then stop releasing air. These allow you to air down all four tires at once while freeing you up to perform other pre-trail tasks. The downside is that the air release process is still somewhat slow.

3) Valve Stem Removal - My preferred method is using an EZ Deflator like the ones offered by @arb4x4 or @currieenterprises. The devices screw directly onto the valve stem and then allow you to remove the valve core itself (the mechanism that holds the tire's air pressure). These devices also have an integrated air pressure gauge, so while you can still only do one tire at time, the air removal process is much quicker and you are ensured that you have the desired air pressure each and every time.

How Low Can or Should You Air Down

This is a much debated topic and if you ask 10 different off-roaders how much they air down you will probably get different 10 answers. The bottom line for me is that you should air down to match your vehicle needs, terrain and driving style.

Things to Consideration When Airing Down

• Vehicle weight - The heavier the vehicle the less you typically need to air down

• Tire Type - While most off-road or all terrain tires are designed to be aired down, the Load Range has a direct impact on the sidewall stiffness and the ability of the sidewall to flex. Load ranges are typically C, D, E, with E being the stiffest. The stiffer the sidewall the more air will need to be removed to achieve the the same amount of flex as a lesser Load Range tire

• Terrain - One of the biggest considerations is determining grip level required for the specific terrain you are traveling.

Learning What Works for You

Learning what works for you in any given situation is a matter of trial an error.

If you are just starting out on a basic trail without major obstacles, you could lower your air pressures 5 psi at a time and see how you like the ride. For example, if you typically run 35 psi on the road the next time you venture out onto the trails simply lower your air pressure to 30 psi. I recommend, so that you can truly get a sense for the process, that you start the trail run at your normal pressures and then after a mile or two lower the pressures in each tire to your desired initial level. Even at a 5 psi reduction, you will feel the difference. You can continue to lower the psi in 5 psi increments until you find your vehicle's and your personal sweet spot given the terrain.

If you are venturing directly out into the rock climbing realm or know you are going to face significant obstacles along the way, then you'll probably want to take a bigger leap in air pressure reduction. Starting out at 20psi and working your way down from there may be the way to go.

WARNING: Depending on your driving style and experience, I do not recommend going lower than 12-15 psi. Unless you are running bead locks, which mechanically lock the tire's bead between layers of the wheel, the primary issue to be concerned with is that if your pressure drops to low you could run the risk of unseating the bead of the tire or cutting the tire from the wheel contacting the ground caused by too much or an unexpected compression.

Of course, the terrain and conditions have a lot to do with determining just what the perfect amount of air vs grip equation is going to be. But as with anything else, this comes with experience. Don't be afraid to experiment to find your sweet spot.

Airing Back Up

It is extremely important to air back up after the trail so that your tires are properly inflated when heading back onto the pavement. It can be extremely dangerous to drive with under inflated tires especially at highway speeds. In order to avoid driving with under inflated tires for prolonged periods of time you will need to have a method for airing up your tires after you leave the trail.

WARNING: Under inflated tires can cause many different issues including:

• Damage caused by rubbing due to clearance of the wider aired down tires

• Increase tire temperature and potential overheating of the tires with prolong driving on pavement

• Increased tire wear

• Reduced fuel economy

Airing Back Up Options include:

• Identifying a service station with an air pump not too far from the trail head. If this is your option, I highly recommend that you pre-check the air pump to see if it is operational before you head out on the trail. Before I had my own air system it was not uncommon for me to struggle to find a service station with a workable air pump

• Having and integrated small DC air pump (or carrying a portable one) with you so you can use your vehicle battery to run the pump.

• Carrying a mobile CO2 canister such as a @Powertank system. This is a great system and one I use and highly recommend. It makes airing up a breeze and reducing the time spent considerably. And, as a bonus feature, you can also reseat your tire beads on the trail or run air equipment as well.

Summary

While airing up and airing down can be a little bit intimidating when you are just starting out, not to worry, after a bit of experimentation and a few reps you will down like a pro.

Hope to see you on the trail!