Air pressure for Beach Sand?
#1
05-29-2006, 10:36 PM
Air pressure for Beach Sand?
What do you guys recommend deflating the tires to when offroading on the beach? I am going to Hatteras tomorrow for a ride and just got back from fishing offshore there for the first time. Saw a guy in an FJ crusier filling air back upi and spoke to him briefly. They have nothing on the H3 at all. Thanks for the input
#2
05-29-2006, 10:56 PM
RE: Air pressure for Beach Sand?
Letting the Hot Air Out of Tire Talk
Tire Pressures for 4-Wheeling
Experiences Playing in the Sand
I guess I should cut those reluctant to lower their tires down to sand pressure a little slack. My first time onto the beach in San Felipe, Baja, I did the air pressure trick, with a little unwillingness, and wasn’t sure it was really necessary. Then, over the next three or four years, I would first tackle the mellow white stuff at full street pressure and when all my power, skill and finesse failed, I would let ‘em down and move ‘em out. Me, low range and low gear, would struggle along at a whole five MPH. Deflation they defied resistance as I sailed along in high range, OD, at whatever speed I chose! Time and again, year after year, I tested the softies with the same undeniable results. Low tire pressure just plain works in the sand!
What Affects Optimum Sand Tire Pressure
Optimum sand tire pressure is a combination of many things, of which old husband's tales are least productive. However, your tires, their construction methods and materials, what your car weighs, how it is loaded, and wheel width all play into the sand-pressure tire formula with predictable results. For this article, I will neglect tire temperature which I suppose could be critical if you test below freezing and play at +80°. Why low pressure works and how to determine your best sand pressure follows.
Why Low Pressure Works
It’s a simple fact, which some diehards still deny, the bigger the footprint, the softer the stuff you can travel. Mother Nature knows it. Take a look at the feet of camels, polar bears and marsh birds. They are big and spread out to distribute their weight over a larger surface area. For those who say skinny, hard tires are better for snow, mud or whatever, please tell me why they don’t use ten-speed bicycle-type tires on snowmobiles? Sand rail people and mud boggers know big feet work better too! With that out of the way, lets take a look at tire pressure and footprints.
Tire Pressure and Footprints
Right next to your wheel, on the tire, find the small black print that specifies maximum load pressure. For example, my BFGoodrich Radial All-Terrain T/A 30x9.50R15LTs state 1990 pounds at 50 pounds per square inch (PSI) cold. Most folks, generally including those who install tires, run them up close to this, and neglect the actual term, "MAX. LOAD" pressure. The street pressure, TREAD FOOTPRINT figure below represents Coyote assessed over inflation.
Do you really need maximum load pressure?
Consider that standing flat and level (static), loaded the way you normally run is one thing. Now further consider you lose full tread width contact as the 4X cruises at higher and higher speeds. Centrifugal force tries to increase the diameter of the tread. You only have to look at dragster tires when they light 'em up to convince yourself of this tire reality. The sidewalls tend to hold the outer edges closer to their static diameter than the center of the tread and hence the center of the tread spins into an ever increasing diameter with increased speed. In other words, while moving at highway speeds, the tire is trying to run more on the center of the tread than the edge. That’s why I feel my full width, static contact test (described below) is conservative. My tire life and wear pattern prove putting more rubber on the ground increases longevity.
Full tread width contact, street pressure
Since this article deals with sand tire pressure, see a back issue of Ecological 4-Wheeling for full details on how to safely determine your exact, full tread width contact, street pressure. Summarizing Tire Pressure, April, 1990 4-Wheeling, you don’t want to overheat the tire and should only be able to slip a business card under the outside and inside edges of the tread less than 1/4 inch. Reprints of past 4-Wheeling articles available for $4.00 each.
Follow along with some arithmetic that
Tire Pressures for 4-Wheeling
Experiences Playing in the Sand
I guess I should cut those reluctant to lower their tires down to sand pressure a little slack. My first time onto the beach in San Felipe, Baja, I did the air pressure trick, with a little unwillingness, and wasn’t sure it was really necessary. Then, over the next three or four years, I would first tackle the mellow white stuff at full street pressure and when all my power, skill and finesse failed, I would let ‘em down and move ‘em out. Me, low range and low gear, would struggle along at a whole five MPH. Deflation they defied resistance as I sailed along in high range, OD, at whatever speed I chose! Time and again, year after year, I tested the softies with the same undeniable results. Low tire pressure just plain works in the sand!
What Affects Optimum Sand Tire Pressure
Optimum sand tire pressure is a combination of many things, of which old husband's tales are least productive. However, your tires, their construction methods and materials, what your car weighs, how it is loaded, and wheel width all play into the sand-pressure tire formula with predictable results. For this article, I will neglect tire temperature which I suppose could be critical if you test below freezing and play at +80°. Why low pressure works and how to determine your best sand pressure follows.
Why Low Pressure Works
It’s a simple fact, which some diehards still deny, the bigger the footprint, the softer the stuff you can travel. Mother Nature knows it. Take a look at the feet of camels, polar bears and marsh birds. They are big and spread out to distribute their weight over a larger surface area. For those who say skinny, hard tires are better for snow, mud or whatever, please tell me why they don’t use ten-speed bicycle-type tires on snowmobiles? Sand rail people and mud boggers know big feet work better too! With that out of the way, lets take a look at tire pressure and footprints.
Tire Pressure and Footprints
Right next to your wheel, on the tire, find the small black print that specifies maximum load pressure. For example, my BFGoodrich Radial All-Terrain T/A 30x9.50R15LTs state 1990 pounds at 50 pounds per square inch (PSI) cold. Most folks, generally including those who install tires, run them up close to this, and neglect the actual term, "MAX. LOAD" pressure. The street pressure, TREAD FOOTPRINT figure below represents Coyote assessed over inflation.
Do you really need maximum load pressure?
Consider that standing flat and level (static), loaded the way you normally run is one thing. Now further consider you lose full tread width contact as the 4X cruises at higher and higher speeds. Centrifugal force tries to increase the diameter of the tread. You only have to look at dragster tires when they light 'em up to convince yourself of this tire reality. The sidewalls tend to hold the outer edges closer to their static diameter than the center of the tread and hence the center of the tread spins into an ever increasing diameter with increased speed. In other words, while moving at highway speeds, the tire is trying to run more on the center of the tread than the edge. That’s why I feel my full width, static contact test (described below) is conservative. My tire life and wear pattern prove putting more rubber on the ground increases longevity.
Full tread width contact, street pressure
Since this article deals with sand tire pressure, see a back issue of Ecological 4-Wheeling for full details on how to safely determine your exact, full tread width contact, street pressure. Summarizing Tire Pressure, April, 1990 4-Wheeling, you don’t want to overheat the tire and should only be able to slip a business card under the outside and inside edges of the tread less than 1/4 inch. Reprints of past 4-Wheeling articles available for $4.00 each.
Follow along with some arithmetic that
#3
05-29-2006, 11:00 PM
RE: Air pressure for Beach Sand?
You are required to decrease tire pressure before entering the beach ORV driving corridor. Tire pressure is critical for successful off-road driving. 12 p.s.i is recommended. Friction may cause pressure to increase while you drive making it necessary to stop and reduce pressure again. Your beginning tire pressure should not exceed 15 p.s.i.
Always check tides before entering the off-road corridor. Portions of the beach may be impassable at high tide.
If you feel you are in danger of getting stuck - check your tire pressure and let air out if necessary; try backing up in your tracks before moving ahead. Do not spin tires, this will only cause the vehicle to dig in.
Do not speed - excessive speed endangers you, your vehicle, other beach users, and wildlife. Experienced beach drivers know that a slow, steady speed and correct tire pressure are more effective than faster speeds.
[IMG]local://upfiles/111/FC5D3577DE7F4A41BAE06AF23C3A4264.gif[/IMG]
Always check tides before entering the off-road corridor. Portions of the beach may be impassable at high tide.
If you feel you are in danger of getting stuck - check your tire pressure and let air out if necessary; try backing up in your tracks before moving ahead. Do not spin tires, this will only cause the vehicle to dig in.
Do not speed - excessive speed endangers you, your vehicle, other beach users, and wildlife. Experienced beach drivers know that a slow, steady speed and correct tire pressure are more effective than faster speeds.
[IMG]local://upfiles/111/FC5D3577DE7F4A41BAE06AF23C3A4264.gif[/IMG]
#8
05-30-2006, 08:29 PM
RE: Air pressure for Beach Sand?
i would say the wider the better, but sand usually isn't part of most tire ratings like mud or snow. unless you're going to get a sand blade tire, which is only good for sand, i think most tires probably rank about equal.
#10
06-10-2006, 11:38 PM
RE: Air pressure for Beach Sand?
I was in OBX recently (to the north of Corrolla) with my super-wide 325's. It was a blast. I didn't lower tire pressure, but could have used it for dune climbing. Here's a couple pics...
