Attention: TDR Forum Junkies Anyone try running max prerssure in 10 ply Toyo AT's 285-70-17 and acheive the "floating ride" as described in this article?
http://www.iar-80.com/page92.html
Here's part of what is says... ...
We especially enjoy the ability of the Toyo Open Country A/T to float the vehicle over road irregularities, on everything from washboard roads to minor pavement seams. In a vehicle with competent suspension, you can achieve this float by making your tire relatively hard and stiff, so that high frequency road irregularities are passed on to the suspension to absorb, rather than being absorbed by a softer tire. Feeding high frequency vibrations to your vehicle suspension keeps it energized, and in constant micro-motion. This has the advantage of lessening stiction, and it keeps the suspension active, floating closer to its center, as opposed to passively sitting on its bottom until a big low frequency bump comes along. If you're a sensitive driver, you can feel when you've managed to achieve this ideal state of suspension float. It's a magical, almost ethereal feeling, as if you were floating (even flying) above the road surface. It's similar to the feeling you get when you drive fast enough on a washboard road so that you are flying from crest to crest, with your tires never sinking down into any of the lateral ruts.
To achieve this magical float, you have to dial in the tire hardness very precisely, so the tire is hard enough to pass high frequency road irregularities on to the suspension, yet is not so hard that your ride becomes harsh. Generally, we have found that the best air pressure to use is the maximum rated cold tire pressure printed on the tire wall (this is usually significantly higher than the vehicle sticker's recommendations for tire pressure). Interestingly, truly magical float is such a subtle, precise phenomenon, that we can tell when our tires have lost merely 1 psi of pressure (as most tires do over time); the vehicle's suspension no longer floats magically, and instead becomes leaden, dead, soggy. It feels as if the vehicle is sinking into each road irregularity, rather than flying over them, and with each upward road bump the vehicles feels more like a heavy truck and less like the buoyant flying machine it did when the tires had merely 1 psi more in them.
Adding more tire pressure to make the tire harder, in order to achieve this suspension float, actually makes your ride smoother (contrary to the popular belief that lowering tire pressure and softer tires make for a smoother ride). A good suspension can dissipate the energy from road irregularities more quickly than a typical soft tire, which has lingering overhang due to the reactive nature of its compressed air springiness and its hysteresis-rich rubber springiness trading energy back and forth, with long time constants, after the original road irregularity has past. Thus, if you rely on a typical soft tire to absorb a single impulse road irregularity, your seat and body will feel the lingering aftereffects of the road bump long after that bump is past, which magnifies your perception of the bump, and also gives it a leaden, heavy quality (the temporal lingering of the energy is equivalent to adding heavy low frequency booooom to what should have been a quick, sharp, high frequency tick bump).
http://www.iar-80.com/page92.html
Here's part of what is says... ...
We especially enjoy the ability of the Toyo Open Country A/T to float the vehicle over road irregularities, on everything from washboard roads to minor pavement seams. In a vehicle with competent suspension, you can achieve this float by making your tire relatively hard and stiff, so that high frequency road irregularities are passed on to the suspension to absorb, rather than being absorbed by a softer tire. Feeding high frequency vibrations to your vehicle suspension keeps it energized, and in constant micro-motion. This has the advantage of lessening stiction, and it keeps the suspension active, floating closer to its center, as opposed to passively sitting on its bottom until a big low frequency bump comes along. If you're a sensitive driver, you can feel when you've managed to achieve this ideal state of suspension float. It's a magical, almost ethereal feeling, as if you were floating (even flying) above the road surface. It's similar to the feeling you get when you drive fast enough on a washboard road so that you are flying from crest to crest, with your tires never sinking down into any of the lateral ruts.
To achieve this magical float, you have to dial in the tire hardness very precisely, so the tire is hard enough to pass high frequency road irregularities on to the suspension, yet is not so hard that your ride becomes harsh. Generally, we have found that the best air pressure to use is the maximum rated cold tire pressure printed on the tire wall (this is usually significantly higher than the vehicle sticker's recommendations for tire pressure). Interestingly, truly magical float is such a subtle, precise phenomenon, that we can tell when our tires have lost merely 1 psi of pressure (as most tires do over time); the vehicle's suspension no longer floats magically, and instead becomes leaden, dead, soggy. It feels as if the vehicle is sinking into each road irregularity, rather than flying over them, and with each upward road bump the vehicles feels more like a heavy truck and less like the buoyant flying machine it did when the tires had merely 1 psi more in them.
Adding more tire pressure to make the tire harder, in order to achieve this suspension float, actually makes your ride smoother (contrary to the popular belief that lowering tire pressure and softer tires make for a smoother ride). A good suspension can dissipate the energy from road irregularities more quickly than a typical soft tire, which has lingering overhang due to the reactive nature of its compressed air springiness and its hysteresis-rich rubber springiness trading energy back and forth, with long time constants, after the original road irregularity has past. Thus, if you rely on a typical soft tire to absorb a single impulse road irregularity, your seat and body will feel the lingering aftereffects of the road bump long after that bump is past, which magnifies your perception of the bump, and also gives it a leaden, heavy quality (the temporal lingering of the energy is equivalent to adding heavy low frequency booooom to what should have been a quick, sharp, high frequency tick bump).
