Two of the earliest examples of tire ashtrays I have been fortunate enough to own would fit here. This is speculation, but the story has surfaced enough times to create a mild concern for myself and some other collectors. This one has a glass bottom with a metal tire attached. It shows 5 different tire treads available. Cracked or chipped inserts, badly damaged or warped tires, scratched advertising on painted inserts, etc., will have a negative effect on the value of any tire ashtray.
Prices vary greatly in different parts of the country and also depend on many variables.
Always remember to let your pocketbook be the guide.