If your talking rims they are the same, with the caveat the some 250 rims had bigger spoke nipple. You can drill them out and your in business.
Now if your talking wheels, thats a different story, some 500 and 250 wheels are interchangeable, some of the older wheels may need to have spacers built. From my experience pretty much 89-02 250 and 89-04 500 on could be made to work easily. the primary difference, older wheels had only 1 drive side bearing and used 22 mm spacers, later wheels used 20 mm spacers. I've used 86 wheels on late model stuff, making my own spacers, which is no big deal, if you opt for something like that make sure they have disc's. I think Kawi is the only supplier for disc's and they are way expensive, so go with the 89 to 02 stuff and make it easy on yourself.
There wa a company called east coast wheels that had Talon hubs for like $125 each, I bought 6 and laced up spare wheels.