Mosey, got them from a local shop that sells/repairs small commercial mowers/trimmers/saws. They also have a few of the Z commercial mowers. The wheel was expensive, around $50 for one, but considering that I've gone through 2 -3 $20 wheels, I figured it would be worth it to try it out. It's guaranteed after all.../w3tcompact/icons/wink.gif.
Well, the short story is that I bought a older used Long 5' finish mower that only had the 2 rear wheels and no front at all. You adjusted with the 3pt height. I fabricated some braces and bought some yokes from a mower catalog and welded it up. I ran into the rear wheels of my tractor hitting these so I had to add 8" to the pin mounting brackets on the mower. My yokes where plenty big and I have used a combination of large nuts and washers as spacers on the rod the wheel rides on in the yoke. With this new tire, I should be able to remove many of the nuts and just have a few washers.
The yokes I bought a few years ago and if I recall they aren't that $$. Just depended on which mower they went. Some had nearly the same specs, but because they were for a certain brand mower the price was +30%. Because I made the bracket around the spec of the yoke/shaft height/dia I went with the better buy. There are several outfits that wholesale mower parts like this, never could find a website for them, but any good mower shop should have a catalog you can go through.
good luck..
gary