Jim, I understand where you are coming from agronomically, but operationally there isn't much sense in even owning a grain cart if you aren't going to use it in the field, and combining corn without one is terribly inefficient. 

I respectfully submit that there is a world of difference between 50,000 lbs on an axle with four tires with something like 500 square inches of contact patch per tire at 13 psi and 20,000 lbs on an axle with four tires with maybe 25 square inches contact patch per tire at 105 psi.  I find it hard to believe you don't realize the fallacy of your comparison.  There is also the fact that many of the heavy machines are not on tires at all.  

I'm not quite sure what I think about the question of driving on the row or between.  I sure prefer to have all the stalks standing in the spring instead of mashed down by being run over.  As long as it is not trafficed wet I think I would consider the tire traffic the lesser of the two evils.