Mine's a GT1554 with the 54" mower deck. Not sure about the tires, but that's a great point. I got it late in the season last year so I only mowed the more grassy areas, but I have some hills I'd like to mow at least a little way up and there is some woody-stemmed brush on it, though not too many thorns. That's a great point for me to keep in mind, though. It was a great purchase and does a great job on the roughly 3 or so acres I'll be trying to keep mowed regularly. Definitely look forward to input on a diesel real tractor one of these days. If you've never been there, the website tractorbynet is a massive source of info on tractors. I had been toying around with the idea of buying a bigger - 50 hp range - tractor shortly after we bough the property, but decided not to get into such a big expense right away. I'm glad we didn't because I really don't think that's a realistic need for what we'll be doing, though I am also a big advocate of buying more than you ever think you'll need on pretty much anything I buy because there will be that time you wish you had more if you went smaller! Just a guy trait, I guess, but if you can have your equipment/stuff do less work than it's capable of, i.e. work at 75% capacity as opposed to pushing the functional limits all the time, I think you get better longevity from it. At least that's my theory!