Fire Chain

Fire Bars are ringed versions of Fire Bars that only appeared in the Mario Kart series.

Mario Kart: Double Dash!!
Fire Bars first appear in Mario Kart: Double Dash!!, they appeared in Waluigi Stadium, and Wario Colosseum. They act a lot like Fire Bars, except that they are not attached to a block, nor their fireballs are connected to each other, instead they are spinning fireballs that attempt to burn a racer that comes in contact with it.

Mario Kart DS
Fire Bars reappeared in Mario Kart DS, they appeared in Wario Stadium. They play the same role trying to burn any racer to slow them down.

Mario Kart Wii
Fire Bars reappear in Mario Kart Wii, they are found in the Waluigi Stadium retro course, and the games Bowser's Castle. Their behavior remains unchanged, however they have a three-fireball ringed versions in Bowser's Castle.

Mario Kart 8
Fire Bars reappear in Mario Kart 8, they only appeared in the Wario Stadium retro course. Here they are once again the main obstacle along with normal Fire Bars.

Trivia

 * The behavior of these Fire Bars are very similar to how Circling Boo Buddies behave.