Hard Rubber Tire with a Hole
Semi-Pneumatic tires refer to a class of tires made of molded denser rubber and rubber products with a hollow core. Not terrible as lawn mower deck tires, but are rarely seen anymore. Airless tires compete and are lighter, foam filled tires compete and are better. They sell under the name Carlisle Reliant and aren't any cheaper or more expensive than its' competitors. Resistant to cuts and very tough, they don't have much give. Seen occasionally on Ebay, they sell for around $75 each and more. Sounds like a lot, but they do work on landscape equipment and they continue to sell a few every year in that market.