Don't misunderstand me. I have a 30 HP B-series Kubota. I can't believe the amount of work it's done. It's the single best machine I ever bought. Mine has a belly mower and FEL and R4 tires.
But it's not going to "work the ground" by the acre by pulling plows and discs. I've tilled many acres and turned sod into seedbeds. And nothing does better at preparing a garden -- even by the acre. I'm just challenging the notion of a 25 HP machine, that also has a mid-mount mower and is used to mow, being "designed" to double as a "tillage" machine.
Most people growing vegetables simply need a rototiller. That's the simplest and most effective piece of equipment. So just put a tiller on it. That's all the ground-engagement you need out of this size machine. And you don't need to over-think the tires in order to have the necessary traction for a rototiller.
It really depends on the ground, doesn't it?
At home, I have this dark sandy ground. Sure, I can just throw a tiller at it and it will make for a great seed bed either way. It's mostly sand after all.
Now, moving 40 miles north, where I have the other place at and it's now this hard clay ground. Putting a tiller directly at it, it like you're trying to till a paved road with it. It just ain't going to work that well. Trust me, I've done it. Biggest reason I built the subsoiler as I didn't have a plow at the time.
That's why people will plow the ground first and the run either a tiller over it or a chisel plow, depending on what they're trying to grow on said land. Plowing the ground is also used as a way to protect the land during the winter time.
Vegetable farming is not only thing these tractors can do. A lot of people will also maintain orchards and vineyards with these smaller tractors. Again, running chisel plows, subsoilers and other specific ground engaging implements made for orchards and vineyards.
It's a tractor, it will do the work as long as the implements are matched to it. Will it be as fast as a bigger one? Of course not, but the smaller one will do the work where a bigger one might not even be able to fit there in the first place.
It can also pull trailers.
To the OP, I apologize for derailing the thread. Just trying to make a point that small tractors can farm too. I'll stop now. Back to tires.