The "big box" tire stores tell me my 10 year old stock/factory Michelins need to be replaced, not because of lack of thread, but because of cracks (alot of them) both between the threads and on the shoulders and sidewalls.

I drive about 10K miles per year, almost all it freeway.

If I had the money, sure I'd replace them now, but I really dont. However, if I REALLY should replace them now, I will.

What do you think I should do?

 

The cracks mean that they are dry rotting, and yes, they probably need to be replaced. It is going to be cheaper to replace them now than later on down the road if you have a blow out and have to replace more than just the tire. Check craigslist for used tires, it is a lot cheaper buying tires used than brand new.

 

Wow, 10 years. I will be thrilled if I can get even half that age out of my Michelin's.
I would say that given the age and the cracking, it is time for a new set.

 

I don't think now is the time to replace them... I thing the time was five years ago. For your safety and everyone else on the road you should replace them.

 

Ummm, almost 90 to 100k miles on them and dryrot. Yes it may be time for new ones!