I recently began bicycling with a used 1996 Diamondback Wildwood 18 speed bike and I need to upgrade the pedals. I took one of the pedals out and measured the diameter of the threads with a digital caliper and got a measurement of .554 inches. Am I to assume I'll need 1/2 inch replacement pedals? Can I upgrade to 9/16 pedals which have better availability?

Thanks in advance,

Greg M.