Glad I stumbled upon this forum/thread. I should pick up some of those tires, while I still can. The ones on my two POW-R-PRO's are very hard.
Here's what I use to keep the yard from reverting into a field:
1974 General Electric Elec-Trak E8m 36"
19(69-74?) General Electric Elec-Trak E15 42"
1964 Hahn POW-R-PRO 22"
1965 Hahn POW-R-PRO 22"
The 1965 Hahn developed a split in the aluminum deck that I'm going to get patched this summer, then have the deck powder coated.
Since the points burnt up on it, it's getting an electronic ignition upgrade as well to prevent that from happening in the future.