The problem with the adaptors is the wheels are hub centric. If you look at our rear axles, the center is tapered about 1/16" thicker in the center where the wheel goes, so the wheel has a tight fit. If you would have an adaptor made, the adaptor would need a centering ring for the wheels to sit on. This ring would have to be less than 1/16" thick. It would be too hard to machine an adaptor this way.
You can buy lug centric wheels. This would make the adaptor easier to make, but how would you center the inner wheel??
I would have preferred an adaptor over replacing my rear axle if it was possible. But I don't think I would have the inner wheel stay tight and balanced.
I got rid of the steel 19. 5's and the tires. I'm currently runnung some stock 17's . The rotating mass, fuel economy, noise from the Bridgstone drive tires, and bad balancing was killing me.
They looked cool, but it wasn't worth it.
There is lots of 19. 5 wheels on e-bay now. They are almost all direct bolt 8 lug. Lots of forged aluminum choices. I will try some forged 19. 5's in the future since they are light and more true than the welded steel wheels. As much as I like the look of the 245 Drive tires, I will go with 225 steer tires next time. They will suck in the snow, but the steers will be quieter and better on fuel. The 225's will be at least 20lbs lighter per tire which is better for braking , accelerating and fuel economy.
I will keep the stock 17's with mud terrains for the snowy weather driving.
There's my future plan when I have money again. But I will never go the steel wheel route again!
Garry