When to replace tires due to age

This is usually a fairly easy call. Older tires will develop very small cracks in the sidewall. The significance of the cracks is what I normally use to judge whether an 'old' tire set needs to be replaced. I've only ever seen one tire develop a leak just from age, and it was coming from one of these sidewall cracks.

Tips, Guides & Resources For Keeping Your Car Up & Running In Jacksonville FL | Tire Outlet

 

Look them over closely. FWIW 5 years is peanuts.

 

Good info here. These are some extreme examples but it gives a good visual

what DRY ROT “looks like” on automotive tires (sometimes hard to see) - YouTube

 

10 years

 

Your car is 5 years old. Although it's rare, the tires could possibly be older. Here's how to check.

For my money, 5 years is when to start inspecting them up close, particularly if the car gets a lot of sunlight/no garage parking.

 

I've got some snow tires with build-date of February, 2010. They were first installed in November of 2010. Last winter we used them, they "look" fine still, maybe the slightest cracking commencing (I'm myopic, macro vision my super-power...), and they still have around 7/32" tread depth.

Last winter I was struggling going up one steep/snowy grade, decided, it's time. Even though they look good, guess the rubber is losing it's pliability, and grip.

 

Snow tires harden and lose any relative advantage vs. fresh all-seasons by age 5. You'll slide off the road long before the tread is worn to replacement indication.

All-seasons are harder to begin with, so you get a little longer.

 

The vehicle the tires are mounted on is irrelevant. As is the miles the tires have traveled. It is the age of the tires themselves. The biggest concern is the UV degradation, which is being minimized by the fact you keep the car out of the sun for the most part.
The next concern is aging due to temperature swings which, again is being mitigated by keeping the car garaged and your location.
The third concern is the flexing of the tires through use that keeps the compounds mixed (don’t ask me to explain that process as I couldn’t grasp it completely at the time it was explained).
Tread depth is completely irrelevant in this situation, as it is the aging and deterioration of the compounds that the tires are made of.
Based on the information you’ve provided and the seminars on this subject I have taken part in (conducted by engineers who have actually investigated tire failures) I wouldn’t worry too much right now and WOULD replace them at the 7 year mark.
HOWEVER, I would not (if they were on my car) leave them on if I was intending to make an extended trip with the vehicle.
Additionally, the degradation of the sidewalls would not necessarily be visible to the naked eye. So please, don’t go by appearance.
I have had a front blowout at highway speeds on a tire that looked completely fine but had degraded due to age AND (believe it or not) low use. Trust me, you don’t want to experience that! That’s why I took the the time to attend those seminars. I can’t explain the processes at work but I understand them now.
Personally, being an owner of a Prius and putting ~3000 miles a year on it, I will be changing out the tires at the 5 year mark.

EDIT: Just thought of this: if your like most of the Gen 4 owners, additional point to replacing them is You Don’t Have A Spare. Just picture yourself on the wrong part of the south side with a flat. FWTW

 

Our Prius and both of its sets of tires turned 5 this year as well. I know I'll be buying a set of tires this fall, I just haven't decided if it's going to be a new set of all-seasons, or a new set of winter tires followed by new all-seasons in the spring. Our usage pattern is changing, might not need the extra traction insurance going forward.

 

I think you’re a wise person.

 

I don’t know where you’re located, but this past winter here in NW Illinois the few times I needed to venture out in the snow and ice, the all-season original equipment tires didn’t fail me in any way. Of course, being retired and living in a relatively small “city”, I have the luxury of picking and choosing when I venture out.

 

i replaced the oems at 40k. now at 85k, i'll have to look up how old they are. surprisingly, they (michelin energy saver a/s) hardly look worn.
garaged and mostly low speed driving, i can't decide when i'll replace them.

 

Well we got the car in part to support my wife's ultracommute, 175 miles each way along the eastern seaboard. The snow tires mattered a few times in the first couple of years.

The biggest question mark in my head is that we just switched from some not-snowy La Niña years to a ?? El Niño pattern this year, so this next winter could be worse than the last few.

 

Yipes! THAT is a long commute! One crazy storm could easily pay for the snow tires. Of course, if you have luck like mine, if you put the money into the new snowshoes, it won’t snow for the next five years.