How I deflate tires for off road use

If you’re thinking this is an odd title for a post, I’m guessing you’ve never deflated 35″ tires to go 4×4 trail riding. If you have, you know the problems with the traditional method of pushing a valve stem in and holding. Going down to 15 psi can take up to 5 minutes, and you have 4 tires to do. Not fun, especially if you do this often. But first things first, why would anyone deflate their tires?

Why you should air down

Better traction – As you reduce air pressure, you increase the surface area contact patch on the ground, providing more traction. More traction equals less slipping, a good thing on any surface.
Better ride – Less air in the tire provides a cushioning effect when driving over rough roads. This is especially noticeable over severely washboard roads.
Less wear and tear on the suspension – A corollary of a better ride for us is a better ride for your suspension components.
Less wear and tear on the trail – Airing down a tire will reduce the amount of pressure a tire places on the ground (because the contact patch is larger, but the vehicle weight has not changed), reducing your impact on the trail.

Why you should not air down

Increased risk of a tire coming off the rim – Low air pressure means your tire can literally come off the bead of the rim, especially when going around corners. So take it easy and obviously carry a spare tire.
Increased risk of sidewall laceration – Deflating a tire creates a noticeable bulge, which increases the risk of a sidewall laceration.
Decreased ground clearance – I’ve never measured, but I’m guessing one inch lower.
It may simply not be needed – I err on the side of caution and generally don’t start lowering tire pressure until I’m not getting the traction I need. Good tires coupled with low range gearing will get you far.

How to air down

Method #1: Stick something, like the back of a pencil type tire gauge, into the valve stem and hold it there. Repeat 4 times. This method should not be ignored mainly because it’s free. If you air down once per year this is the method I would use. I’ve owned a Milton for 15 years and it’s still working.

Method #2: Screw on tire deflators. These little units screw onto each tire and depress the valve core, exactly like the method above, except you don’t have to press and hold anything and all 4 tires deflate simultaneously. They automatically stop at a pressure you determine. I use Trailhead deflators and they work fine.

Method #3: Remove the valve core. Removing the valve core will greatly speed the release of air, but you can only do one tire at a time. I’m not convinced there are time savings vs. method #2 when you consider all 4 tires. I own the ARB E-Z Deflator and it works well, but I find myself using the Trailhead deflators most of the time.

I run my 35″ all-terrain tires at 30 psi on the road. I’ll go as low as 15 psi for serious trail riding. If all I want is better ride for a long washboard road, maybe I’ll go down to 22 psi.

ARB has a great post about airing down tires for trail riding: https://arbusa.wordpress.com/2011/10/26/the-lowdown-off-road-tire-pressures/