[MagicRat]

This subject has been discussed before here at AF, but it is an interesting one and deserves revisiting.

First of all, tires do age. The rubber compound becomes harder and effectively less grippy over the years. This means that old tires has somewhat less traction. This is not an issue for normal driving, but it makes emergency manoevers somewhat more dangerous. Emergency stops will take more distance, and your can will not handle hard cornering as well.

Also, when tires get really old, (over 10 or 15 years) the rubber outer layer can start to crack. If it cracks enough, the outer layer, which has the tread might peel-off the carcass or body of the tire.

Finally, in my own experience, really old tires seem to be weaker, and cannot handle the heavy loads they could when they were new. When heavily loaded they might break an belt and go out-of-round, or might 'blow-out' with little warning.

But in your case, 4 year old tires are definitely not a hazard at all. IMO tire age only becomes an issue at 7-10 years. It is also important to occasionally examine your tires for other hazards, such as nails or debris imbedded in the tires, strage looking bulges and uneven wear, which may signify other safety problems.

Finally, tires will not all deteriorate at the same speed. A tire that is in storage in a dry, dark garage, and rarely used will age more slowly than one which is subject to sunlight, heat and daily driving. You can see this in many cars....... the 4 driving tires may look aged and cracked after many years of driving..... but the spare tire in the trunk looks as good as the day it was made.

I have a good example of this in my garage. I have a set of 13-year-old Cooper tires that have never been used, ever. They look perfect, no blemishes, and the rubber is as soft and pliable as a new tire. But my daily -driver car has 6-year-old Michelins that are getting pretty badly cracked and hard. Obviously the Cooper tires would be a safer choice to use, even through they are far older.

I did have tires in my Jeep that were 23 years old by the time I changed them They still worked okay, but were getting cracked. My brother's Jeep has 25 year old tires (rarely driven) that look and work like new. But this is an exceptional case. For most tires, imo 10 years is the upper limit.

BTW, a few years ago, 60 Minutes did a story on this issue. IMO they deliberatly sensationalized this issue, and exaggerated the hazard of older tires. They gave the impression that tires aged just as fast when new, in a dark warehouse as they do when driven in the summer sun (not true) and gave the false impression that tires were lethal ticking time bombs after 6 years.