On my 2014 Frontier with 3/4 tire life left; I picked up a nail/spike that could not be repaired. No choice but to order a new tire, so ordered the same Goodrich rubber the truck came with OEM. This would leave me with 3 tires with 3/4 tread and one new one. I thought about it and realized my spare was full-size...! So I talked the shop into moving the spare off the steel rim onto the alloy and mount it on front with other new one. So now I have TWO new ones on the front and a 3/4 tread spare! I can live with that! The shop balked a bit but finally realized I would not order new tire UNLESS this was done. So they did it and no charge for mounting or balancing the spare... Got lucky there. A plug for Big O tires!!! Plus they matched the price for same tire at Costco...
Bear in mind this would probably not be a viable option if the spare was 10 years old or some such...