The number one rule is rule to keep Hi-Rail Gear truck tires on rail is to make sure the rail gear wheel base allows the tire or tires to remain in contact with the rail head when traveling on its sharpest curve. If the tire falls off the rail in the curve then the Hi-Rail Gear has to support the weight of the truck until the tire can make its way back up onto the rail head. The consequence is that the tire gets badly damaged by the sharp edge of the railroad rail. Far too often this process is the norm on some railroads as opposed to the exception. This practice is not only dangerous but very costly to the railroader. The location of the rail wheels must be engineered properly so the truck will negotiate the curve and keep the tires on the rail head.