You need to measure how much room you have. Mount the rims and check to see if they stick outside the fender or rub anything. The back is pretty easy, the front, you need to checked centered as well as all the way to stops left and right.
Now, like your rear rims, you need to convert inches to millimeters (mm). Tire sizes today are as an example 225/55 R 16. What this means is the tire (at thread) is 225 mm wide, the sidewall is 55% of the 225 mm, the R means it's a radial tire and 16 is the rim size.
Your rim width, rear, is 10 inches. That is 254 mm, so a 254/ tire would be the same width as the rim. If the rim edge is still inside the fender well, then a 254 or smaller tire should also stay in the fender well. tirerack.com will let you browse tires by size and tell you what size rim you need. For front, you need tires that will mount on a 9 inch rim and rear, ones that mount on 10 inch.
Now, for vertical clearance.
http://researchmaniacs.com/Calculate/TireDiameter.html will let you calculate the diameter of the tire you are looking at. The radius is half the diameter. Now, you need to know how far it is from the center of the spindle/axle when your shocks are at full compression, to anything it might come in contact with, like the fender well. If that distance is smaller than the radius of the tires you are looking at, well, you will risk rubbing.
Basically for pro-touring, you want as much rubber as you can fit in. There are a lot of ways to control the "rake" look. Tires are just one of the, you already have some off set with the two different rim sizes, but if you put the same basic tire size on each, you get that offset. (example, 255s front and rear), other wise use the calculator above to check and decide the difference between front and rear for each tire size you look at.