Groover wrote:
If you are like me throwing away a $200 tire that has never been on the ground is painful. Then again, you are only averaging 7,300 miles per year so you are not going to wear out 4 tires in the normal 6 year tire lifespan anyway so there really is no point going to extra effort to put this tire into the rotation plan. Just do the cheapest thing for the spare that you are comfortable with. I would rather 4 good tires with no spare and plan on calling road service in an emergency than plan on putting a 10 year old tire on the ground.
What I have found in my research, is the tires that are used last longer than the tires that sit. Something about the flexing of the rubber keeps the molecules - for lack of a better word - healthy.