Airing down?
Based on my Compressor Recommendation thread, I now have a nice ViAir 450P compressor to air back up. So now it's time to start thinking about airing down. I'm use to airing down my jeep to 15psi w...
Forum Discussion
You need to remember, their charts are for highway use at normal highway speeds under normal condition. Tire manufacturers do not calculate or publish charts for abnormal driving conditions such as airing down for slow driving in soft conditions.
Tires can only disappate heat so fast and tire flex generates heat. Air pressure for specific loads are calculated and tested to make sure the heat generated by the tire flex has a chance to disappate and not over heat the tire. It is the tire construction and bead surface that limits the maximum pressure which by limits max load capacity at normal speeds.
By slowing down, the tire will generate less heat for the same loading. So to generate the same amount of heat at the lower speed, you can carry more load. Some tire manufacturers provide the chart to allow this such as you found on the Michelin and Firestone. However, these charts are still for highway driving, not on soft surfaces.
Off roaders, farmers, house movers, and remote heavy haulers have been airing down tires for years for better traction and higher flotation. Since so many variables such as soil hardness, moisture content, rock size, rock sharpness, etc, it would be impossible/impratical to have a chart.
If you need a chart to reference to make your self feel comfortable about air down, then it may not be for you and suggest you stay on hard packed surfaces.
Tires can only disappate heat so fast and tire flex generates heat. Air pressure for specific loads are calculated and tested to make sure the heat generated by the tire flex has a chance to disappate and not over heat the tire. It is the tire construction and bead surface that limits the maximum pressure which by limits max load capacity at normal speeds.
By slowing down, the tire will generate less heat for the same loading. So to generate the same amount of heat at the lower speed, you can carry more load. Some tire manufacturers provide the chart to allow this such as you found on the Michelin and Firestone. However, these charts are still for highway driving, not on soft surfaces.
Off roaders, farmers, house movers, and remote heavy haulers have been airing down tires for years for better traction and higher flotation. Since so many variables such as soil hardness, moisture content, rock size, rock sharpness, etc, it would be impossible/impratical to have a chart.
If you need a chart to reference to make your self feel comfortable about air down, then it may not be for you and suggest you stay on hard packed surfaces.
