The wheels in the recent pictures are the American TTO version with the 5x5 bolt pattern. The fronts are 15x5, with BFG Radial T/A's. Tire size is 215-70R-15, and are about 26.5" tall (off the truck) with a tread width of approximately 6.5".
The rear wheels are 15x7 with Firestone Firehawk Indy 500 tires size 255-70R-15. They are 28.75" tall off the truck, with a tread width of 8.5".
I prefer the way they look for back tires since they have more of a square shoulder and look beefier. They're mounted with the white letters on the front side, since I didn't care for the design on the blackwall side. I colored out the letters with a chisel point Sharpie, and seal it with ArmorAll Extreme Tire Shine Gel. It lasts about a year before needing any touch up. It would have been easier to mount them blackwall out, but I've always been a bit nuts about wheels and tires. If I ever make another change it will be to swap out the front wheels for 15x7's. I'd still mount the smaller tires for a staggered look, but they would appear deeper and probably look better than the 5" rims.
15x8 TTO's will fit just as well, but I don't like the design of the wheels. They have an extra machined space in front of the spokes that just doesn't look right to me.
The 5 spokes on the front of the truck in the picture with the Buick wheels on the back, are 1968 era 15x6" Dragmaster mags. I was surprised they fit over the disc brakes very nicely with just a tad of light grinding on one of the calipers.