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Discussion in 'Technical Q&A' started by Circle K, Feb 17, 2021.
$900 for the rear set, I do feel a difference on grip
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I think a tire is good for 10 years, from date of manufacture. The manufacturer might say change at 5-8 years of use, because the tire may be two to three years old at the time of purchase, so 5 years later the actual tire age is 7 to 11 years old. Many wholesalers sell truck tires that have been in the warehouse for 5 years, they may sit further at the distributor warehouse, and they expect they will be used and worn out about 5 years later.
I think for a car with lower milage stored in a garage, a 10 year from date of manufacture would be the time to schedule a change. The remaining tread would not be the factor for low use cars. And inspecting for sidewall cracks carefully after year 5 would still be a required. If the car is regularly used in wet conditions, then bring the change date forward to 8 years, as there will be a harder compound as the tires ages, and wet weather is where that performance hit is meaningful.
On the other end of the range, changing tires at year 5 from manufacture that show no deterioration would be a waste of resources.
I did a bit of homework on the Carrera GT.
Making a sweeping right hand turn at near 100mph in a 45mph zone might well be a problem of loss of control, although it was being driven by a race car driver so one can speculate the driver error was not the main cause. On the other hand, someone doing this type of speed on the road is making a form of driver error, so I wouldn't be so sure a loss of control was a tire problem. Of course, the tires were 9 years old, with a Porsche recommended change at 4 years. So it is unknowable if the tires contributed, but not out of bounds to be a factor. But the widow of the car unsuccessfully sued Porsche based on an unsafe suspension design, so Porsche may have been defending its car with the tires excuse for legal defense.
My guess is the mid engine Porsche is an acknowledged widow maker for even seriously experienced drivers, and all crashes in this car are typically catastrophic including those with no tire age issues. Too much power for a mid engine car with no traction control aids. 200 of 1200 cars made were totaled in the first two years, ie. all with new tires less than two years old. Yikes. The longer term end result was a legislated use of driver stability systems.
The Bugatti Veyron required tires changed every two years or 2,500 miles.
Clearly these exotic car tires are changed as the manufacturer has to ensure the cars full speed potential can be safely used at any time. It is not like the tires should self destruct when used at normal speeds for longer time/mileage. But I guess an ultra high performance/high speed car is beyond pretty much everyones driving skill, and one would not want to add another risk factor of aging tires to the mix.
But on the whole, I don't think this high profile accident argues for really short tire change out intervals on less than extreme cars.
I know that turn well, and it’s not a 45mph turn. It’s a 90* left turn and I believe it’s marked 15 mph. 100 mph is way to fast for that kind of turn, no matter what kind of car or tires.
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How would you notice any difference when it is incremental over the years? Have you put new tires on it to compare?
Even if you drive like the proverbial "little old lady to the grocery store", there is the possibility of catastrophic failure at speed on the freeway. The aging process is mostly internal, what you cannot see.
Sixteen year old tires? That must be a record!
It's not a track car, and I avoid driving around LA at 100+ mph. I agree that new tires are better than old tires, but I don't avoid high-speed runs on local freeways. I also frequently check the air pressure. Low pressure puts a greater stress on the sidewalls.
In the old days people did not replace tires until the tread was worn, or the tire had obvious visual degradation. There did seem to be more people with flat tires, something you rarely see today. Speed limits were also higher. Quality control at tire factories must have improved. This may be a case of people simply having more money to spend, with the benefit of fewer flats and presumably much more safety. Or perhaps tread wore out more quickly making replacement necessary fairly soon. I wonder what Ferrari owners did in the 1960,s regarding tires ?
In the late 60s and 70s Ferrari tires wore out way faster than 6 years, many would have had wear ratings around 60 if they had wear ratings then. We were not too concerned about mileage then with many in use, including mine, as daily drivers.
For me, 6 years and they are tossed. By then there is usually a greatly improved model, as was the case when I swapped MPSS tires for MPS4S.
Some interesting perspectives in this thread. I am a firm believer in age limits for the tires on my cars and replace accordingly. I have to admit that I do cringe a little when I discard a tire with 90% of its tread left but I also can feel how hard they are getting when they hit 5-7 years so away they go. It does make me think back to my youth when in high school in the late 60's with my first car that I ran $12 recaps to keep me "rolling" and never even thought about the quality of the tire. My how times have changed.
I would say your credibility as an "Engineering Consultant", is now put into question.
I recently saw an old “Jay Leno Garage” episode, I can be wrong, it showed a mint condition 60’s, Ferrari, not his but owned renowned collector. Still had its original tires and they still took it for a spin
I really don't think so, but I hope you enjoy your new tires.
For any readers of this thread that have a background in chemistry or chemical engineering, here is a link to a technical article on tire aging: link
Tires are made from 3 different rubber formulations for the tread, the sidewalls, and the inner liner. Absent any road damage, tire aging normally occurs from the inside due to oxidation of the rubber in the “wedge” area, the area where the sidewall joins the tread. The inner liner is designed to retain the air (21% oxygen) used to inflate the tire. As the oxygen diffuses through the inner liner, it promotes oxidation of the rubber in the wedge area causing it to weaken and ultimately fail. Like most oxidation reactions, the rate increases with higher temperatures and higher partial pressures of oxygen. Higher temperatures result from both the outside temperature and the flexing of the sidewalls under driving conditions. Studies have shown that tire failure is higher in the southwest region of the US. Higher quality inner liners will reduce the diffusion of oxygen to the wedge area and thus prolong the life of the tire. Using 100% nitrogen to inflate the tire will also prolong the life of the tire.
I'm still looking for you to provide a technical article or document that supports the OP to continue driving on 14 year old tires, or your Z4 with 17 yo tires.
My degree is in chemistry and, as previously stated, I swap all tires at 6 years.
From the article: "This article will review the research that has gone into quantifying the rate of oxidation the steel belt rubber oxidizes in different climates from tire samples retrieved from consumers’ vehicles. The information obtained from the field is then compared to data collected from various resources attempting to develop accelerated tire aging protocols."
That article has zero to do with tread face rubber hardening, which is what will have a direct impact on traction and grip for cornering and braking. I don't care if the sidewall and rubber inside of the steel belts is good if the rubber of the tread is age hardened and traction/grip is reduced by 30% - 40%. That article does nothing to convince me to lengthen my current tire replacement interval of 6 - 7 years.
If tire grip is your main concern, then by all means replace your tires at a frequency that your deem appropriate. This is what is done for race cars and Challenge cars where driving is done close to 10/10. However, that does not mean that the tires are unsafe for every day driving.
Grip is very noticeable, as is ride, as the rubber ages and becomes hard. But because it happens gradually, most don't notice the dramatic difference until new tires are fitted. But the greater concern is structural integrity, which is unseen, and no visual inspection can tell what is going on, that is why both car and tire manufacturers offer a reasonable replacement recommendation. Doubling or tripling that recommendation seems ill advised.
https://www.safercar.gov/Vehicle-Shoppers/Tires-Rating/Tire-Aging#:~:text=Some vehicle manufacturers recommend that,specific recommendations for your vehicle.
From the NHTSA
What is meant by “tire aging”?
The structural integrity of a tire can degrade over an extended period of time. When that occurs, tires are more prone to catastrophic failure, which could, at best, cause an inconvenience, or, at worst, lead to a crash. The degradation of a tire occurs over time, mostly the result of a chemical reaction within the rubber components. That aging process can be accelerated by heat and sunlight.
How do you detect when tires have become unsafe?
The effects of aging may not be visibly detectable. Since there is no standard test to assess the serviceability of a tire, even an inspection performed by an expert may not always reveal the extent of tire deterioration.
When does NHTSA recommend that tires should be replaced?
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.
We are talking about aging and how it relates to grip and structural integrity. Race cars change tires based on wear and grip. My friends with race cars can easily go through a couple sets of tires on a weekend. They are rarely concerned with tire age, they don't get enough wear for that to be a concern.
Old tires do become unsafe with age. That is a fact, but you choose to believe otherwise. It is also not visually detectable, so that is why there are recommended age limits to reduce risk of catastrophic failure. Grip is also a concern, as the rubber ages it becomes harder, and loses significant dry and wet grip.
Filling the tire with nitrogen? The study clearly states that this is not a viable path "use highly purified nitrogen which is not readily available to most consumers". I honestly doubt that one is so spendthrift so as save a few bucks on tire and ready to spend hundreds on Air-Liquid products.
What this study also tells us is that between 5 and 8 years, tires are 10 times more likely to catastrophically fail. No data for >10 years old tires. The study also highlights that faster kinetics makes this dramatically worse. Are we buying Ferrari in order to avoid "faster kinetics"?
What may be marginally risky on a sedate car could be deadly in any of our cars. We are on Ferrari discussion board, any advice should be provided accordingly.
Chemistry major too. Wife too. 5 years max for our tires. Wife says they gotta go; who am I to argue?
It really is not worth the risk IMO...T
The one thing about grip for old tires is that it directly affects braking distances. So with older tires the need to make an emergency stop will take longer and eat up more distance, which you may not have.
So when tirerack sends you guys tires stamped from 2 years ago do you send them back?
Not usually. Because the primary reason that happens is the tires are limited production, either overall or in that particular size (so no choice in the matter). I always ask, if it is not stated in the listing, usually when they are over one year old it is in the listing description. Rarely have I ever received anything more than 8 or 9 months old. The only exceptions being the Pirelli PZero Corsa. I think Pirelli only makes the 430 Scuderia ones every 18 months to two years, so its always a crap shoot.