Discontinued tire

[Bill-SD]

I have one bad tire on my '91 535i, the others have a lot of tread left. The tires are Michelin Pilot xgt V4 R15. It seems these tires are discontinued. That seems to happen every time I look for tires! Anyway, would it be bad to replace just the one tire with another Michelin tire, but different model? If not, how about if I replace two tires? I hate to buy 4 when I only need one.

Thanks for the help!