I've was looking at a 4020 listed on e-bay today and noticed that the 60" deck had a lot of black scuff markings apparently from the front tires of the tractor. Is this an indicator that something was out of adjustment? Is there a design issue? I suppose the tires may have been the wrong size but that seems unlikely. Just asking as a point of interest and to see if there is an adjustment I should check on my tractor.