Whether rolling along or sitting pretty in the garage, tires do have a shelf life

Dear Tom and Ray:
I have a 1995 Buick Regal that I purchased new before I retired. I drive the car approximately once a month. The car has 55,000 miles and is always kept in the garage. My question is about tires. The tires are the original Goodyears. They appear to be in excellent condition except for some very minor cupping. Should the tires be replaced because of the age?
— Arthur

Ray: Unfortunately, yes. There are some things that wear out only when you use them. That's why my brother's work clothes are still brand spankin' new.

Tom: But there are other things that degrade over time, whether you use them or not. Rubber is one of those things. It's degraded by ozone in the air. And over time, it dries out and cracks, and loses its pliability.

Ray: Some people say: "Well, to protect your tires and make them last longer, you should pay money to have them filled with nitrogen instead of air. That way, you're ridding the insides of your tires of all ozone." Good idea, right? Except that only protects the insides of the tires. The outsides of the tires are still surrounded by air with ozone (unless you park it in a hyperbaric garage).

Tom: And the conventional wisdom these days says that tires should be replaced every six years or so, even if they're not worn out. Add to that the fact that your tires are cupped, which can compromise emergency handling, and I'd say you're way overdue, Arthur.

Ray: You got more than your money's worth out of your current set, Arthur. So bite the bullet and spring for some new rubber. And if you're still driving this car in six years, you can celebrate your good fortune with another new set of tires.

(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)