Both air & ground applications work fine.

In my experience however, even w/12-13" tires, one of the problems (if it is a problem) is that in taller beans the sprayer tires will grab the bean stems & pull them down from adjoining rows. Your tire itself may be squarely planted between 2 rows, but the track made will be wider due to those adjoining beans coming down with it. Even the JD sprayer w/fenders will grab them down lower & make a path. I suppose if you're in 30"+ rows that aren't canopied, you may have a better chance. But, at this time of spraying aphids, most fields "here" are well canopied.

I feel that both air & ground have their advantages & disadvantages.