While some dealers will tell you that it's a good idea to use used tires with a different tread pattern, don't think about it. If you drive four tires with the same tread pattern then you need to consider a good cash service for a car and your ride will be smoother and tire wear will be more even over time.
Aside from the fact that money is so tight that you have to settle for odd patrons, do yourself a favor and make sure they all meet the profile requirements. Next to the tread, look at the side of the tire. You can check frequently asked questions about the used tires for the alignment service.
You want to make sure that the sidewalls look solid and that there are no holes or other signs that the outside of the tire has been damaged in any way.
While logically you can't expect the sidewalls to look brand new, it's possible to get used tires that have obviously been properly serviced. This means that with a set of used tires you are more likely to get good service.
You have to remember that some repair shops and tire dealers have a good stock of tires that are used most often. Many of them are tires that are sold when the seller buys a new set of tires.