Spare rim is for temp service only, tires only have a four year service life, I write this because I didn’t realize the full size spare had a cheap rim until I removed it to inspected the tire
By practice I would normally replace the spare tire with the when installing a new set with the least worn of the set.
I was told by the tire shop my 10 inch wide tire spare wouldn’t work because the depression was too narrow but through fellow forum members experience say it will
I will personally buy a regular non temp rim and find a used tire to mount to it as long as it clears the height of the rear bumper.
The diameter of the tire should match so the differential is not strained but if you have a different diameter wheel it should not be used on the drive axle, meaning if you have a flat on the rear you would need to mount one of your same size wheels to the rear drive line and the off size wheel to the non drive axle , within reason to make a wheel change on a busy highway is never convenient but the correct rotation should be made within a reasonable amount of time out of caution and safety.