Yeah, the bigger 23x8.50-12 rear tires are readily available, both in turf or ag tread. I have a set I dragged out yesterday. They don't look too bad for their age; we'll see if they hold air for more than a few minutes. Right now, I'm trying to pull a 4' drag harrow around a small field I'm reviving, and traction is an issue. I'm also trying to figure out some more weight for the back. I can buy wheel weights for $150, but I'm cheap and poor, so I may try to make some concrete ones.