Flat Tire is a member of the local bicycle gang. He initially calls Lincoln's hand-me-down bike "lame" in the episode "Hand-Me-Downer".
He also appears again in "Lincoln Loud: Girl Guru", as one of the boys seeking advice about girls from Lincoln in order to impress a girl named Mollie. Lincoln then suggests that Flat Tire should take Mollie to a funeral, seeing how Lucy likes them. We later see him ask Mollie out, and the latter ends up rejecting him out of disgust. Flat Tire then glares at Lincoln for suggesting that he should take Mollie to a funeral.
Flat Tire has fair skin, freckles, and brown hair. He wears a yellow t-shirt, blue pants, and a purple bicycle helmet with a star symbol on the front. Similarly to Lucy (and her male counterpart Lars), his eyes are entirely concealed by his hair and helmet.