You could make up some cardboard wheels to represent width and off set. Many Speedster use the long IRS rear and could benefit from different offsets of steel wheels BUT there seems to be none available (especially in chrome). Different offset alloys are more readily available. You get to choose 4.5x15" or 5.5x15" and that's about it. 4 and 5/16" (or 4 and 1/4") seems to be the standard backspacing. Easy to push them out with longer lug bolts and wheel spaced - moving them back away from fender lips NOT so easy.