Model Trucks › 20" wheel Backing Ring 1/25 R299 Image 1 of 1 20" wheel Backing Ring 1/25 R299 $3.75 Set of 2 Resin cast backing ring, 20" wheels. R299By Plaskit.Includes 2 backing ring.For use with AMT/Ertl 20" tires. Quantity: Add To Cart Added! Set of 2 Resin cast backing ring, 20" wheels. R299By Plaskit.Includes 2 backing ring.For use with AMT/Ertl 20" tires.