Yeah I’ve got similar vintage x-ice, still over 6/32” tread depth, NO cracking, but 11 years on the car come this fall, and manufacture date another 6 months or so.
I think (?) they must be more concerned about something like heat build-up. I had a flat on my FOCUS, ordered a new tyre, the TEMP was on and did maybe 125-140km in the 2 days before it got fitted - and didn't show any sign of wear at all. And no - at 10 years later, can't recall if it was front or rear.
Yeah, I don't know how the 50miles 50mph max caution came about. I had a flat on our 6 years old Pathfinder last year. We were away, and I had to drive at least 50miles on a temp mostly slower than 50mph in the city before I can get a new tire on. We bought the car used, so I am not sure if the temp tire was used before me, but the tread looked new. After getting the regular tire back on, I just stored it back under the car. Not sure if I should consider replacing it anytime soon.
^ "Google it!" Most of the OEMs have done what OEMs do - which is to advise the victim to consult the spare tire manufacturer for the deets. There's usually a bright yellow placard or label somewhere on or near the "space-saver" spare. It's probably just a "Lawyer Label" but it's out there..... The Donut Spare Tire-Everything You Need to Know Spare tire - Wikipedia
I’m staying out of this argument but like Alan said I have driven more than 50miles on a donut. A QUICK google bore results of 50-300miles and someone also stated the “reason” for the limit was that the grease in the bearings was stressed by a space saver and overheated thus causing transmission and gear box issues. Go figure.
If you are near or over the gross vehicle weight and it’s very hot the space saver can actually overheat because the thick compound doesn’t handle heat well, in normal or cold temperatures it wouldn’t concern me as long as the space saver is full
Here is one ref. Not saying they are correct. But, I just wanted to know if I should replace our compact spare on Pathfinder or not. At least according to this AAA answer, the problem is not the tire, but the car. So, maybe using the same temp spare on multiple occasions for no longer than 50 miles at a time may be OK? How Long Can You Drive On a Spare Tire | AAA Automotive