My front tires are in real bad shape and I am going to replace all 4 with same exact tires which is Michelin Energy MXV4 Plus 235/65R17 bought in 2009 and 35k miles ago.

Should I throw away the spare tire which appear in good shape based on the fact that is about 10 years old and use one of the current rear tires as spare. My rears are not in great shape but still I think they can handle a few thousand miles and I don't plan to use spare for long time if I ever need to.

What do you guys think?

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2003 BMW X5 3.0i - 163k miles