I'm new to this site and to these forums. I don't know if there is a certain protocol to be followed when someone asks a question, seeking help, so I'll treat this one as though it had been asked by one of my students and not give the answer out on a "silver platter."
Imagine the wheel to be a circle, and a spoke of each wheel is the radius.
Hint: what do you know about the relationship between a circle's radius and its diameter?
Polya said to solve a problem, you must first understand the problem completely. Do you? If not, try making a diagram of this situation.
Once you understand the problem, form a plan of attack on the problem. To find the difference in the lengths of the spokes, you must first determine the lengths of the spokes, and then subtract the smaller length from the larger length.
Try that, and let us know how you fared!
