I work at a tire shop and just from my experience i say always get matching tires. When it comes to load/speed ratings as well as tread design. I always get customers the same tread design if they need one or two new tires. Its not terrible to have two different tread depths for an all wheel drive car, such as low in the front, more tread in the rear. As long as its not one low in the front and one with thick tread in the front. Hope this helps.

 

its not terrible along as they are close, a worn almost bare tire vs a brand new tire will be bad. A slight difference would not be ideal but it would work. But usually on a awd car all 4 tires wear at the the same rate.

 

The guy mounting and balancing the tires showed me a patch on one of the rear tires that still had good tread left. He said it was a really bad job and probably would have failed sooner rather than later so I guess it's good I got all 4 in the end. I took the one good tire with me and now I'm looking for an stock rim to mount it on so I can have a full sized spare.