Hi all,just bought my first tractor:p and I have two questions, first how can I tell what year it was made? Two,it has the 13.6x16 turfs on back and r-4 on front(wrong size) should be 24x8.5x12 and they are 23x8.5x12. should I take them off they look like new,or can I buy r-4's for the back that...