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Perry Mack
Airing Down Chart
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Dean Bradley
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Dean Bradley
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Dean Bradley
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Dean Bradley
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Dean Bradley
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Dean Bradley
By Dean "Old Skool" Bradley
Successful four wheeling is all about traction; and the most important piece of equipment on your vehicle determining how much traction you have – is your tires. Creating traction extends beyond the drivers own abilities to operate their vehicle. Knowing the correct tires for the varied terrain you will be navigating is crucial to gain a positive outcome when the four wheeling gets challenging. Yet with tire options as varied as the terrain we travel, making the right choice can be tough, however there is one option any four wheeler can use to improve their odds of success when negotiating that next trail.
It’s the air pressure in your tires to be exact, that’s right, running the correct psi (pounds per square inch) of air in your tires for the terrain you will encounter is crucial to overcoming demanding trails and the technical obstacles that are lurking out there waiting to take a bite out of your 4x4 experience.
This technique along with the ability to manage on trail tire repairs are off-road essentials that everyone traveling into the back country should develop and be ready to apply should the need present itself.
So you're out for a day of adventure in your 4x4, traveling the back roads with the family but the FSR's (Forest Service Roads) with their washboard-like surface are beating up your truck, not to mention your kidneys, so badly you're forced to slow down to a crawl. So what's an adventurous and outgoing family like yours to do? Well some already know the answer and for those who don't, it's as simple as reducing the air pressure in your tires, that's correct it's not a misprint, the fact is by lowering the air pressure in your 4x4's tires you can turn that rough and rowdy ride into something more attune to a Cadillac. If you can master the art of airing down, it may in fact allow your 4x4 to travel over rough roads as if on a magic carpet of soft air.
Is there a magic pressure to give your 4x4 a Cadillac like ride? I'm sorry to say there is no perfect pressure for all obstacles or terrains. It’s not as simple as finding one number and sticking with it, yet it’s possible to get close relatively quickly and then adjust as needed if the traction is still proving elusive.
Generally dropping your tire pressures to about 20 psi for FSR's will allow full-size trucks and SUVs to realize an improved ride and greater traction in soft terrain like mud, sand and snow. Those of you running L/T tires on a lightweight vehicle such as a Jeep, midsize truck, or SUV could even begin at 15 (psi) for similar gains. A few items to note regarding reduced air pressure are:
1.) ALWAYS TRAVEL AT REDUCED SPEEDS WHEN AIRED DOWN, especially on loose surfaces, particularly while cornering, and take care to recognize the different reaction time a tire with reduced air pressure has.
2.) DO NOT TRAVEL ON HIGHWAYS WITH REDUCED AIR PRESSURES, as an unsafe condition of increased tire temperature and an increased chance of losing a bead could lead to a tire failure with disastrous results. Always air back up to appropriate tire pressures before commencing highway travel.
Learning this simple technique of reducing tire pressures can really make a difference in turning a rowdy ride into a pleasant drive and if you practice a couple of basic rules of safety - you’re good to go.
So some of you must be asking yourselves how can this be, what’s the catch? Well there is no trick, it is just good old physics at work. The best analogy I’ve come up with is the comparison to a snowshoe, by that I mean if you lower the air pressure in a tire, the tread actually expands it’s footprint on the ground similar to a snow shoe’s enlarged size as compared to a basic snow boot. Review the accompanied tire prints to really see what’s happening with the tread of an aired down tire, you might just be surprised at the increase of tread print.
Airing down can not only make the difference between a rowdy ride or pleasant drive but may also be a factor of success or failure on terrain that is of a more challenging nature. Many a time, I’ve seen four wheelers reluctant to air down below street pressures only to continue to struggle and search for the traction that their fellow wheelers obtained so easily just by dropping another 5 or 10psi.
Unnecessary damage may occur to the vehicle or terrain through this inability to realize that tire pressures for on-road do not make for success off-road. Experience has shown that 4WD vehicles such as Jeeps, midsize trucks and sport utility vehicles, running light truck radial tires of the A/T and M/T persuasion, typically in the 30” to 37” range, operated by seasoned four wheelers, routinely air down to 10 psi and below, on typical weekend wheeling trails in terrain such as loose dirt, gravel, snow, sand and mud. Heavier full-size trucks and heavily loaded SUV’s (over 6,000lbs loaded) may want to stay above 10 psi due to their increased vehicle weight.
Treading lightly over the terrain is another aspect or bonus to airing down, which due to the growth of the tread print distributes the vehicles weight over more ground (larger tread print = less weight per square inch). In addition, with the reduction of air pressure a tire becomes more apt to distribute it’s casing not just over but also around an obstacle, thereby offering even greater traction and lessening the impact on the terrain.
As a note of safety, there is one particular model of wheel in which airing down does not work well, and that is the 16.5” wheel. Due to its design, the advantage of airing down is lost, as losing the tire bead (having the tire slip off the wheel) is a common problem. So for those of you still operating with these wheels, maintaining highway pressure is best.
One more quick tip - running through these fundamentals of four wheeling for the first time is easier accomplished in the driveway than on the trail.
So the next time your looking to gain some traction on the trail or simply soften the road ahead, try airing down your tires to find the perfect pressure that will enable your 4x4 to climb that next hill with ease, all while offering a smoother ride.