second handers, some ones having ya pants down kiddo as only 2 of them will be useable as ilovewilly has said.
You are best buying new because a least then you know where they are from, as a cheap quick fix they might be ok.
I used to get 2nd's or ones from the factory where they would have something missing or misspelt due to machine defect, pay £20 a tyre but buy 3 sets of tyres a year, had brand spankers on now for nearly a year and loads of tread left plus only cost me £80 p/t delivered.