(ET) Ground compaction from elec traks

[Christopher Zach <czach computer org>]

Got a question: I've noticed that over the years since getting my E20 
that the grass quality has slowly gone down. Digging with the tiller I 
have also noticed that my soil is hard as a rock up top, getting better 
about 6-7 inches down.

Is the tractor causing my soil to "hard pan"? If so, what can be done 
about this? My tires are original, and are hard as rocks. Would putting 
new tires on fix the problem? Or should I till my yard every year or so?

Chris