The tire becomes part of the suspension
At ordinary road pressure, a tire holds its shape and carries a vehicle on a relatively small patch of rubber. Letting air out makes the tire’s sidewalls bend, so more of its tread presses against the ground. Because the truck’s weight is spread over a larger area, the snow beneath each tire bears less pressure at any one point.
That matters because snow can support a vehicle only while it remains firm enough under the load. A narrow, heavily loaded tire can break through the surface and sink into softer layers. A broad contact patch is more likely to stay on top, much as a snowshoe spreads a person’s weight.
Why go as low as 2 PSI?
On specialized trucks built for deep snow, very low pressure can make the tire deform dramatically and conform to uneven terrain. That gives the tread more opportunity to grip rather than spin against a small patch of loose snow. The useful pressure depends on the vehicle’s weight, tire construction, and snow conditions; 2 PSI is not a general setting for ordinary trucks.
The tradeoff is control and durability. With so little air supporting it, a tire can flex heavily, and on firmer ground it may handle poorly or be more vulnerable to damage. These vehicles therefore use low pressure as a terrain-specific tool, not as a way to improve driving everywhere.
The striking result is that the tire’s shape does some of the work: instead of forcing the truck to power through snow after it sinks, it helps keep the truck from sinking in the first place.
