Toward the end of last season I noticed that my rear tires on my ztr were doing some damage to some yards while turning, slowing, and going around obsticals. I mentioned this to my now "ex-dealer" who looked at them and then told me that they still had about a year to go. There has to be 20% or less tred left (still some but not much). At the beginning of the year the there was no damage to the turf by the mower. Given that the mower does do some damage to some yards should I get new tires despite what my old dealer says?