Anyone know the Rim/Tire combo on Roadkills Crop Duster?

They're M&H front runners and drag radials.

Fronts are 185/75/15. You can see "185" on the picture of the tires in the gallery in the Hot Rod article here. I'd post the picture but Hot Rod doesn't let you link to their pictures. Roadkill Builds a Budget 12-Second, Big-Block 1970 Duster! 40-Plus Photos Here

The rears you can't see any size info on other than "15", which is a pretty easy guess anyway. But, based on the fact that they kept the leaf springs in the stock location, the amount of room they have left and M&H's drag radial selection I'd say they're 275/60/15's. Just my wild-*** educated guess. They're using every inch of the stock wheel wells, and with the stock spring location that means a 275 because the car isn't high enough to run wider than that. Plus M&H has a pretty limited selection.

Drag Radials