2016 Chevrolet Sonic - replacing one or two tires after a flat

I got a flat tire on the left rear do I need to buy two new ones or can I just buy a used tire

Can the flat be patched? If so, do that. Or did you drive it until the thing disintegrated?

You don’t have to buy 2 new ones but it really depends on how worn the tires are. If they are 2/3rds of the way to the wear bars, yup, buy 2 new, put them on the rear. Consider buying 4 new and rotating them every time you change oil.

I wouldn’t suggest a used tire for most car since those four rubber things are the only thing between you and death. harsh, yeah, but good tires are important.

Did I tell you that a bolt is what caused the flat

Replacing more than one tire is rarely necessary, with the common road hazard warranty offered today we replace only the damaged tire.

can you post a better/closer pic of tread? does not seem to be much tread left. but the angle/lighting is so poor i cannot tell. if tread is above acceptable limits than i would replace 1 tire