So I'm restoring an old Raleigh 3 speed, and the tires had a ton of rot on them. I pulled out the tube and the nylon type of material inside the rim also has been rotted to the core. My assumption is that stuff is in there for a reason (to protect the tube from the spoke screws?), so I'm guessing I should replace it. Am I right? If so, do I get it at the LBS or can I get it at a fabric store?