My wife has a 2001 Saturn SC2 we purchased new in 2000. She only has 12,000 miles on this car and the tires look new. No cracks/checks. My question, can these tires be “bad” because they’re so old (8-years)?
Tires do age. See report over here: http://www.aa1car.com/library/tire_expire.htm. The safety experts are advising drivers to replace tires that are 10 years old or more. Of course, maybe only one old tire out of a thousand will ever cause trouble for the driver. So it’s up to you.
When you checked the tires for cracks, did you physically get down on your hands and knees and look at the tire sidewalls while your wife slowly moved the vehicle back and forth?
The suns’ UV rays cook rubber and ones that aren’t used much will deteriorate.
I don’t use my travel trailer as much as I used to (gas$$$) so it sits still for long periods. This is not good for tires.
Rolling the vehicle a 1/2 turn once every three months and covering the tires to keep them out of the sun helps make them last longer.
Same goes for seldom used or outside stored vehicles (Unless they are put up on jackstands and the wheels removed).
Her car sits in the garage so it doesn’t get much sun exposure. She “does” drive weekly (grocery store, etc) but not much. When she backs out of the garage, no signs of cracks, etc. She RARELY takes it on the highway (rarely over 45mph) so even if there is a blow-out it won’t be at high speed. Just goes against my grain to dispose of tires that “appear” to be good. Guess $400 for a new set probably is worth the peace-of-mind 
Yeah, so I have a 1998 Tahoe with a spare carried on the underside of the car. No UV down there. It’s a 1998 spare with full tread. Should I replace it? No cracks visible.
Yes they can be bad, just because of their age, but they don’t necessarily “have” to be bad. If there are no sidewall cracks I wouldn’t worry too much.
There have been quite a few bulletins published recently on the age of tires. The concensus is that the rubber in tires degrades over time EVEN IF THE TIRE IS UNUSED!
Cracks are an indication that the tire is getting used up, but lack of cracks doesn’t mean the rubber is OK. What’s important is the condition of the rubber inside the tire - which you can’t see even with X-rays!!
There are been different age limits stated and my take on this is that if you live in a hot climate (AZ, NM, NV, TX, CA, and FL) the limit is 6 years and if you live in a cold climate (MN, WI, ND, MT, etc) then the limit is 10 years. States in between are … Ah … Mmmmm … inbetween.