Originally there was a rubber band about two inches in width that protected the tube from the motion of the spokes. This band sits at the middle of the rim. Of course, there are longer spokes that enter the rim on the higher portion. There is no band for these. Some use electrical tape or duct tape.
The “tubeless” rims have a quantity of silicone smeared on that rim surface. This works great until it doesn’t – then locating and repairing the leak is difficult.
Insure you use the heaviest / thickest tubes you can find. There used to be tube tires and tubeless tires. The tube tires did not have ridges on the inside that cut into the tube. I don’t believe you can find those any longer. I don’t know if it makes sense to attempt to reduce the rough/sharp edges of those ridges when fitting new tires.
Talk to Universal Tire in Hershey PA or to Coker Tire in Chattanooga TN (same company) for further advice.
Hope some of this helps.
SAFETY FAST!
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids MI 49506-2410
Cell: 616-307-6737
www.universitymotorsltd.com