>Under-inflated tires actually buckle inward when in contact with the 
>snowy ground due to low tire pressure, thereby leaving only the

take 5-10lbs out and widen/lengthen  the contact patch.  This does work fine
in moderate snow, used for years on Michelin XZX summer tires to get around.
Why do you thing 4x4 people air down their tires in soft stuff? Nothing
helps on ice so forget that part. Except good sticky rubber, stud, or
chains.  Tim