The Autobot that transforms into a red firetruck in the original cartoon is Inferno.
Inferno is a Generation 1 Autobot firefighter and rescue specialist whose Earth vehicle mode is based on a Mitsubishi Fuso fire truck. He combines emergency-response duties with frontline combat, making him one of the Autobots most naturally suited to burning buildings, hazardous missions, and battlefield rescues. His red body and ladder-equipped truck mode make him easy to identify.
Inferno first appears in the original animated series during the episode “Dinobot Island, Part 1.” The cartoon presents him as exceptionally brave and eager to enter dangerous situations, sometimes so eager that his combat instincts distract him from his rescue responsibilities. He is also closely associated with the security officer Red Alert.
Hot Spot is the main potential mix-up because he is another Autobot with a fire-truck alternate mode. However, Hot Spot is the blue leader of the Protectobots and later forms Defensor. Springer is a triple-changing Autobot, while Red Alert transforms into a Lamborghini Countach, not a fire truck.