One tire had to be replaced due to damage.
The rest half worn out. Replacement identical model, size etc. So, slight difference in radius due to tread wear. Any problem? Soon will need to replace 3–same question. FWD car.
I’d put it on the rear. If your other 3 are that worn out, why not at least buy one more now for the other side?
I too would put it along with the one opposite it on the rear if they’re not already there. It’s good to have the fronts equal for balance in the handling.
That’s not a bad idea. Then I could use one for the spare. Now, my spare has a different speed rating.