Cal,
Thanks for the reply. I'll see if I can cross reference those tire sizes. I have a set of 215 - 70's that I might try. 
I won't do any plowing until the spring. I leave the food plots up all winter. I have a few pheasants on the property along with turkeys and deer. They all like the corn and soybeans.
It should be interesting plowing, the first time I've ever used a pull behind. I'm going the use a Ford 4000 4cyl diesel, about 45 hp. I hope its enough. Sorry that I'm not using an Oliver, but I don't have one. They're not very common around here. 
Thanks again for your help.
Chris