National Geographic has an interesting article about the case for feathers in Tyrannosaurus.
Tyrannosaurids may have borne anything from a few feathery tufts to decadent coverings of fuzz. The dinosaur’s appearance is open to multiple hypotheses. Scales-only cannot be taken as the default any more than totally-feathery tyrannosaurids can. But given how the story of dinosaur feathers has unfolded, I’d bet on the fuzz.
Read more at Feathers for Tyrannosaurs.