Didn't see the raised oval on the tires, but the rims are stamped 08/19/03.
Looks like this is an 2003 model year. Thanks for the information.
Again, there is no "model year". They can make the exact same machine for five years, with no changes, so they don't use the term model year at all. Cars almost always change from year to year, and tractors frequently don't. Similarly, they can make a significant change in the middle of the year, so knowing the year doesn't matter....you'd need to know the before/after serial number to know if the change applied to your machine or not.
On your wheels and tires, they don't dictate the year the tractor was made, although in your case, it can't be prior to 2003.
For anyone else researching the same question, I can't recall if the B series were made in Japan, and shipped here or not, but many Kubotas of that timeframe were. They added the wheels and tires after the long ship ride here from Japan so the two dates could be quite different. Even if the machine was made here, there's nothing saying the wheels and tires couldn't have been made months before, or after the tractor, and the year of manufacture doesn't match up.
If you want to know what year the machine was built, call a dealer...that's the only way to know, and not guess.