Greetings Chris,
      .......and welcome! I have one of the plows also and you will enjoy it! I also have auto tires and they work fine. Yes, all three are the same. if I were to invest some money in it I think I would run 4-rib tires on the front and a 3 rib on the back.... just my choice. The rear  wheel rides in the previous furrow and acts as a rolling landside helping the plow to track true and straight. Evidently, this plow model also ran a small 10 or 12 inch trailer wheel. i have seen both. Newer plows, if they have any at all, are often running a small steel wheel. I think any tire inflated hard and having sharp treads will do well. 6.00 or 6.50x 15 tires should do fine. I can't even guess what the new tire designation equivalent would be (I suppose I could go down back and look at mine.) 
    Hope you get a chance to run it before snow flies! 
               Cal