According to the catalog I found, the rims on this bike are 27" Araya rims. I think someone told me that 700c wheels weren't used until a while later. In any case, I've been running them around 70-75 psi without any problems, though I'd like to get them around 90. I think the issue is the tires...it's my belief that the wire bead on one side of the tire or the other is a millimeter or two too big, which would make the tires pop out, so once I get some cash I'm gonna get some nicer tires. If that doesn't fix the problem, I'll assume rims and start shopping for some. For now, it gets me around town though.