Renkaista
Renkaista is the elative plural form of the Finnish noun renkaat, which means tires. In Finnish, the elative case marks origin or source, and the plural elative is formed with the suffix -ista/-istä. Accordingly, renkaat becomes renkaista in the elative plural. The form is primarily a grammatical tool and does not carry a separate lexical meaning beyond indicating origin from multiple tires.
The singular elative of renkaat is renkaasta, meaning “from the tire.” The plural elative renkaista is used
Renkaista sits within the broader Finnish case system and illustrates how Finnish nouns inflect for number