Tire is more than likely 80s (I'm not positive they made 2.0 width back then as everything I remember and have owned from shop finds was 1.75) and going rate depends on several factors.
Is it Shinko?
Is it dry/cracked/rotted in any way?
Do you have a pair or is it an orphan?
What's left for tread?
I'd have to say without knowing the answers to the ?s above and assuming it's an orphan it's prolly worth about $15-20...maybe more, maybe less depending of course how badly someone needs it
-No dry cracking or rot, rubber still looks good
-She's an orphan
-Tread is still really good just some dirt stuck between her teeth. The guy I bought it from bought the bike for his daughter about 20 yrs. ago so I'm confident it hasn't been abused.
thats not a shinko, the early shinkos have the gt logo on both sides of the tire, meaning 6 and twelve positions, on the same side. does yours have two ? i cant see a second one.