These tires are a true SKINWALL tire. What is a skinwall versus a gumwall tire? To save weight, skinwall tires have just enough rubber in the sidewall to cover the nylon casing. Gumwall tires have a heavy, thick coating of rubber that completely covers the casing. This is why on a true skinwall you see the "threads" of the casing. What is great about these tires is the "natural" (tan) skinwall is the correct vintage color. Some newer skinwall tires have such a light, blonde coloration that they really stand out as being historically incorrect - but not these - as the pictures show (taken in natural light), these are just like the originals from back in the day.
These tires are made from the original molds from the 1980's - since these tires haven't been made since then, Hwa Fong never updated the molds with the "Duro" name - so these tires are 100% original to the 1980's - but brand new production. These were custom manufactured for Porkchop BMX.
Hwa Fong tires came stock on many quality "bike shop" BMX bicycles from the 1980's. Sometime in the late 1980's or early 1990's they began marketing their tires under the "Duro" brand name. These tires were made from the original molds that were never updated with the Duro name. In addition, these tires are stored in a climate controlled (both temperature and humidity) environment with no sunlight. Therefore, you are guaranteed a soft, supple tire that is mint condition if you want to show, or safe if you want to ride. Hwa Fong has been producing quality tires for many applications, both motorized and non-motorized for decades.