[EarlyTrekker]

…, I didn't make it 500 feet before it disintegrated. So even the spare shouldn't be left to age too long.

Lucky you ”only” made 500‘

Such tires don’t always blow out. But as the tire rapidly disintegrates the “belt” often beats on the fender and $1,000+ is the starting point for the repairs!

 

[EarlyTrekker]

I got 13 years from my run flat tires on my BMW. Had to get new cuz of tread wear, not so much rubber rot. BUT, please note, the car was a "garage queen".

Run-flat tires by design are tougher. “Mere-mortal” tires are in the RED zone no later than 10 years. Ground level ozone and the normal rubber aging processes are considered the two primary factors.

 

[EarlyTrekker]

I would like to see a picture of the cracking that you are asking about.

We each have different degrees of acceptable cracking before we replace a tire for no other reason.

ED

Will also require a well lighted close-up pic to bring out the cracks.

Agreed 6 yo tires with significant dry-rot cracking is young. But I seen a few

 

[EarlyTrekker]

<snip> The only difference is that run-flats have extra reinforcement in the cross-section to help the tires hold their shape without air...

Exactly! Tougher.

But I personally wouldn’t risk my life on 13yo run flats either!

 

[EarlyTrekker]

Ahem, back on topic

Pics of my replaced 9+yo Michelin Defender tires.
(Aged beyond safe sustained interstate speeds)

Heavy sidewall “dry rot” cracking and the subsequent hardening of the tread rubber.
In the last 10mo gravel on the driveway is now cutting and “chunking” out the rubber.

Tires that look like these are giving you their absolute final warning and were already dangerous for sustained highway speeds.

HTH!