Thanks for the good information Phill & Paul.
I think my main concern is getting the correct size. I think I will go with the 5-15 Firestones at TSC. That way I can pick them up on the way home from work and install them this weekend. These tires are a 3 rib desing that seems appropriate for the tractor.
As for correct police, keep them away form me. The rear tires are in good condition but are not the same brands. Other than that the tractor is in pretty much original codition except for an incorret starter switch, no battery box, an enlarged exhaust pipe hole in the hood to accomodate a muffler, and some appendage that someone welded to the axle housings. It also has spent the last 45 years outside so the paint looks a bit rough.
In another lifetime this tractor was part of our small farming opperation in MN. It and my dad retired to a 20 acre hobby farm in 1972 when the state took the farm for a freeway interchange. Since then the tractor has seen light duty as a wagon puller and has a buz saw attached to it for cutting fire wood. The goal is to get the tractor back to good enough working condition to allow the tean age daughters to use it to pull a harrow for preping their riding arena. I suppose this means that I also have to get the electrical system working again as well.
Thanks again, I probably will bug you with more questions as I gradually fix this tractor up.