billyban,There is no source for new rear tractor tires in the 15 inch size. Someone may try to sell you a tire that was designed for a bobcat type piece of equipment, but I don't recomend them because the sidewall stiffness is too great. They won't squat down and grip like a low pressure tractor tire. I looked for over 2 years for a set for a close friend that owns a GT-14 that he wants to restore. I lucked out and found a pair of brand new, old stock Goodyear 27 - 9.50 X 15 lugs at a local tire store. They said they had got them at an auction for a Toro/Wheel Horse dealer that died and they auctioned his inventory. The best part was I bought them for $30 a piece. I can only imagine what they would have brought on e-bay if I would have listed them.