I hope that's a rhetorical question, because an answer is light years away from me! My first guess would be that every other constituent would be proportionally reduced in percentage terms, but I have no real idea. The major constituents make up about 99% of the atmosphere, but that last 1% contains thousands of things.

 

You said it yourself, "8 years in hot/sunny climate (Florida)". That is a LOT different than OP's garage kept in Illinois.. I would expect your tires were like rocks. But not the OP's tires given his situation..

And sure, new tires are always better.. We change to NEW tires for EVERY race weekend in competitive standings situations. But the "cost of providing your cat with proper “shoes” 🙄 is not what everyone would consider "very modest" - to say the least. Great discussion - and simply my opinion.. All the best.

 

Hi, how could I tell the date of manufacture on the tires. My 245/45Z/R18 100WXL

 

little oval near rim as shown

 

Great, thank you. I missed that marking. Good to know.

 

Depends of how you use your Jag. Short low speed around town trips, you're probably OK. If you make a lot of highway trips at high speed then I would go with new tires. No sense in taking a chance.

 

I've considered summer only tires to maximize warm weather performance but I drive this car up until the first snow of Winter (and salted roads) which may be as late as December. I wanted a tire that would not be compromised by the common low temperatures that can drop into the 30s and 40s in early Winter and early Spring. The car is put away when the roads first get salted and not brought out again until a good Spring rain washes away the Winter's residue of salt.

 

Hi, I agree about the concern while driving at high speed. I just checked my tires I have three 26/14 and one 25/14. So, they are six years old. Tires looks good, plenty of treads. So, I'll replace them once I get my stimulus check. Again, thank you. I'm working on securing my Seat Module under the passenger seat that's loose. Broken bracket but works. I read that is a common issue. Dealer wants $850,no way.

 

I'll pile on briefly to say that I have 25 year old tires on my 74 Jaguar and they will be replaced if I ever drive it off the mountain I live on. However, when I purchased my 01, it had low mileage premium Pirellis on it, BUT they had been on for a long time on the very-low mileage car. And, it was in the desert, although parked in the summer I believe. Regardless, I blew out a rear tire on the freeway at about 75+ MPH. It had split right down the middle and it wasn't inflation. I immediately changed out the tires.
An interesting parallel in the boating world: deck shoes lose their grip and the sole gets slippery after about two years. The compound just hardens. It's a bit scary.

 

Rick, does this mean you never drive it or you'll only change the tires after the crash? If the latter, as your server, may I suggest the pork tartare for your main course??

 

6 year old tires are not dangerous! If tires would go bad after only 6 years I believe there would be a law for driving with old tires. There was a test in a Swedish magasin a couple of years ago between new winter tires vs 10 year old winter tires. They were suprised the 10 year old tires behaved so good, they were not far the the new.

 

With a bit more research I came up with these recommendations that in the end put the onus on the consumer (of course). I was looking to see if there could possibly be some form of "integrity test" to sort out if a tire was still in sufficient health to remain in service. There is NO such thing. I do remember years ago that plane wings used to be tested by placing heavy sandbags on them. If they held up then they were good to go. What was eventually discovered was that the weight of the sandbags produced microcracks in the wings that led to failure sooner. Modern testing for wing metal fatigue was changed to sophisticated non-stress testing with ultrasonic, x-ray and magnetic particle devices. None of this is available for tire testing and stress testing a tire with heat and high pressure/O2 will just lead to failure sooner. I think a "tire biopsy" could help diagnose the health of a tire but in the end the cost of doing such a thing ends up prohibitive compared to just getting new tires.

The conclusion of the compiled reference below is that at 6 years you need annual tire assessments by a "tire professional" but even a tire professional cannot detect internal weakness that may lead to failure. At 10 years it is recommended to dispose of the tire. Figuratively and literally YMMV!

I've included the references and a quick summary for those that are interested...https://continentaltire.com/learn/ho...does-tire-last

Continental is unaware of any technical data that supports a specific tire age for removal from service. However, as with other members of the tire and automotive industries, Continental recommends that all tires (including spare tires) that were manufactured more than ten (10) years previous be removed from service and be replaced with new tires, even when tires appear to be usable from their external appearance.

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https://www.bridgestoneamericas.com/...ire-inspection

Depending on how much you drive each year, your tire’s tread may last for years but just because the tread is not worn out does not mean that your tires don’t need to be replaced. Bridgestone, following industry standards, recommends that tires be removed from service no more than ten (10) years after the date of manufacture.

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https://www.tirereview.com/wp-conten...TSAs_Work1.pdf

First is degradation of the rubber compound and material interfaces due to the effects of heat and reaction with oxygen (thermo-oxidative aging). The second is the effect of cyclic fatigue during tire deformation, which can initiate and propagate cracks and separations

The most frequently occurring failure was cracking in the shoulder (55.6 percent), other failure modes observed were: cracking in tread groove (22.2 percent), cracking in base of tread at shoulder (18.5 percent), tread separation at shoulder (18.5 percent). Smaller percentages of tread shoulder blister, tread chunking, cracking in sidewall, sidewall delamination, sidewall bubbles, sidewall deformation at splice

In summary, NHTSA’s main findings with regard to tire aging can be listed as follows: • The aging mechanisms that are most likely to affect the relative safety of a tire are chemical and mechanical in nature. Chemical aging occurs due to the combined effect of heat and oxygen on the rubber compound and mechanical aging results from the stresses and strains that a tire incurs during its normal use. • In the warmer parts of the United States where we have data, including Arizona, Florida, Texas and Southern California, there appears to be a relationship between the age of the tire and the propensity of the tire to fail. • Tire aging failures tend to appear in the high heat states, in the summer months, during the day, while the vehicle is being driven at highway speeds. All of these factors make it more difficult for the tire to dissipate heat, and heat build-up is the main factor in these types of failures.

At this time, the agency does not believe it is necessary for motor vehicle safety to add a tire aging requirement to its light vehicle tire standard due to the following reasons: First, FMVSS No.139 has contributed to an increased robustness of oven-aged light vehicle tires. Our research has shown that oven-aged FMVSS No. 139-compliant tires are more resistant to degradation than oven-aged pre-FMVSS No. 139 tires. Second, light vehicle tires are performing better on the road as reflected in our most recent crash data. Third, a mandatory TPMS on light vehicle tires 30 since 2007 has helped alert consumers to under-inflation, which is also known to degrade tires faster.

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https://www.safercar.gov/Vehicle-Sho...ing/Tire-Aging

Continental is unaware of any technical data that supports a specific tire age for removal from service. However, as with other members of the tire and automotive industries, While tire life will ultimately depend on the tires’ service conditions and the environment in which they operate, there are some general guidelines. Some vehicle manufacturers recommend that tires be replaced every six years regardless of use. In addition, a number of tire manufacturers cite 10 years as the maximum service life for tires. Check the owner’s manual for specific recommendations for your vehicle. Remember, it is always wise to err on the side of caution if you suspect your vehicle has tires that are over six years of age.

 

I had the same issue, so I did a simple test. Full throttle from a dead stop. The rear end was all over the place, so I got new tires the next day.

 

Nobody mentioned this so maybe I am wrong.
A few years ago a tire man told me the government had mandated no more mercury ( might have been sulfur ) to be used when curing the rubber. and that let the tires deteriorate quicker.
Nofking

 

Sulfur is still the most commonly used compound for curing, or vulcanizing, raw rubber during the manufacture of tires. Other compounds - called accelerators and activators - speed the process of vulcanization, but sulfur is still the key ingredient.

 

It hasn't moved in three years and hasn't been over 30MPH for a decade. However, once I get it going in the spring, and I am SO close, the second stop is the tire store!

 

I'm always barefoot on my deck ... can't beat that natural grip!

 

and I rarely am... too many broken toes on deck hardware. That is, if you sail a real boat . on real water

 

https://www.hagerty.com/media/opinio...ut-1200-tires/

This is what Jay Leno found out about old tires from experience.

 

Two items during my years of driving I have never held back on nor spared any expense on….. Tires and Brakes. Our lives depend on it! Why even give it a second thought??? It just doesn’t make sense when it comes to our safety and possibly our lives?? I couldn’t care how good my tires look or how few mikes are on them. Looks are deceptive. Change them when appropriate and sleep well at night!