Over the years of my life and at one time not having many monies i replaced one tire many of times especially if the other one was still in good shape. And with another used tire.
Normally all 4 were shot but hard enough money wise to buy one.
And we all survive.
Today i really do need to replace at least the two back tires on my dodge but will get all four at a cost of 1400. In the last few months had to replace four tires on my other dodge and four on my wives Buick (awd) but only did two. Took a long road to get here. db