Bias v/s Radials dia size

Is there a huge difference in the actual size of the same size tire in a bias v/s a radial. Reason I am asking is I bought radials to replace the bias on they are alot smaller. The bias tire is a Mickey Thompson Sportsman and the radial is the Mickey Thompson S/R Sportsman . Now I have to sell the tires I bought and buy new but would like to know how much bigger I can go or is this not normal. Thanks

Any type of custom wheel/tire deal I always measure one already mounted on somebody else's ride. I've been burnt before by a "26 inch tall tire" and found out it ended up being 24".MT should have good numbers on their site for those.