This is interesting.

When you find a hot tire, what’s the average difference in PSI?

It would be a guess. another way is to look for a bulge at the bottom of the tire..

When towing our trailer the tires on the sunny side of the trailer are usually 3-4 psi higher. I don't know the temp difference but now will take note.

I can notice sun induced temp. in my race car;

You can buy tire pressure monitor systems with independent temperature gauges for as little as $30 from various cheap importers. You just screw them onto the valve stems instead of the caps.

They work pretty well for the price, and are great on something like a car hauler to watch tire pressures and temperatures from the cab. It's always interesting to see the temperature differences from the sun as you note. Here in the winter, tires can be -10C on the dark side and +10C on the sunny side of a parked vehicle.

As to the tire discussion, tires are expensive here in Canada. We run 'em till they bulge or are bald unless we need the performance. I've only ever seen bias ply implement tires actually pop, and they're running at low speed in the field so it's not a big deal.

Talk to a tire shop
 

Tires have a date of mfg on them. If I'm mistaken, they're good for 8 years before the rubber starts to degrade. If you're losing air, it's probably from sitting so much.

Thank you for the reminder - I had forgotten about the fact that the manufacture week and year is indicated on the sidewall.
For the 4 Yokohamas on my car: "0419" So, the 7th year since manufacture started this month. Good to know.
Thanks-

Probably pretty late for the party ...

https://www.yokohamatire.com/tires-101/maintenance-care-1/tire-life

"Every Yokohama tire is designed to last a certain number of miles. However, there are some steps you can take to ensure you get the most out of your tires."

Tire lifespan is event driven and time driven. The event is the number of miles but will a tire degrade even with no miles over time? Yes, but I cannot recall ever reading something authoritative which says X number of years ... From personal experience, I would never trust any tire over seven years.

The manufacturer has instructions. Regardless of the miles on the clock, I read somewhere the manufacturer indicates 10 years is the max, but I would double check that.

Perfect timing as I hadn't seen that page. Straight from the source:
"Yokohama recommends the replacement and disposal of all passenger and light truck tires whose D.O.T. production date is 10 or more years old, even if the tire appears to be undamaged and has not reached its tread wear limits."

Yokohama surely knows far more about tires than I do. Nonetheless, driving my car on tires that are 7 years post-manufacture would not be my personal preference.

Thank you for your post.

For many a daily driver would exceed the mileage limit before 7 years, so that would not be a factor.

However, many os own older classic cars that don't get driven many miles. They also don't see high speeds or agressive use. These can I am sure be kept for longer provided the tires are inspected and look OK.

My 350SL only sees about 1000-1500 niles per season (summer driven only). It had Michelin tires. Because the sidewall date said they were 14 years old, I took it to a Michelin dealer and had them inspect the tires.

They put the car up on a hoist and did a thorough inspection. They said they couldn't find any reason I shouldn't continue to drive on those tires, considering the low stress use they experience.

I decided I would need new tires sooner or later anyway, so bought a new set. This time I went with Toyo, partly because of good past experience, but also due to availability of tires of required size and rating.

Another anedote: I had a set of Kumho tires on my 85 300D. I don't recall the mileage or age, but well before tread was worn, I noticed one tire was losing pressure regularly. I then noticed a large bulge in the side wall while inflating. Put spare on. Then bought my first set of Toyo tires!

You're very welcome.

To wrap this thread up, my 2012 date code Michelins came off yesterday. I pulled them to do a brake inspection and found 2 that had broken cords with polyester actually sticking out between the treads. The interesting thing is the tires were well out of round, but had worn back mostly round. The treadwear indicators were showing at the spot of cord separation, but the rest of the tire was at 3/4 of its original tread depth. The tires actually still rode pretty well. I had been on a 4 hour interstate trip the day prior. I replaced them with Toyos.