Tire wear due to miles driven vs age

Allow me to give everyone a practical demonstration.

Have you ever bought new tires, then noticed a bit later that there is a white film on the sidewall? That’s the waxes that have migrated to the surface to protect the tire in storage. Those waxes flake off after a bit.

Then, later, the white film is back - albeit, less intense? More waxes have migrated to the surface!

Have your tires ever turned a reddish brown? That’s the antioxidants that have migrated to the surface. That flakes off, too.


I can’t come up with a good word that describes it (gel? colloid? suspension?), but there’s even a paper on the topic of “Chemical Addition Migration in Rubber”. Here’s the abstract:

“Migration of compounding ingredients is an important factor in the overall properties and performance of rubber articles containing a number of layers for example, a tire, a hose or a conveyor belt. In certain cases, migration of compounding ingredients before, during and after vulcanization in rubber compounds can be of benefit. For example, waxes and p-phenylenediamines antiozonants rely heavily on the migration mechanism to provide optimum protection of rubber products during service against degradation by ozone. In addition, the dispersion of compounding ingredients such as oil, curatives, and antidegradants can be enhanced by diffusion within rubber. In other cases, however, diffusion across a rubber-to-rubber interface can be detrimental to performance. Diffusion will change the distribution of materials which in turn may result in changes in mechanical properties, loss in adhesion or antidegradant protection, and staining of light-colored products. Thus, a better understanding of the migration of chemical additives in rubber could provide the desired distribution of ingredients for obtaining the optimum compound performance.”

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Michilin tires here got excersized on a weekly or daily driver. Something like 60k miles in 10 to 14 years. It was probably 10 to 12 years. The wore out, but one of them dry rotted and cracked on the side wall before it was all the way done.

They were excersized but failed sooner than the tires of the 90s. Maybe they would have failed sooner if they had not been used frequently? I don’t know.

The 80s or 90s (probably early 90s) Michilin tires on a collector car here are fine with no cracks. The car is never driven.

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I’m going against the grain here. I don’t believe your tires are unsafe and they will be fine to go another year.

The biggest enemy to the rubber in your tires is UV light, the biggest source would be direct sunlight. You stated that the vehicle is garage kept.

It is true that the rubber needs “exercising”, but driving a few miles at least once a month should be enough for that. The web site was referring to vehicles that are driven once a year or less. If you drive at least once a month for a few miles at a time, you should be OK for the next year.

Look at the tires. If you see fine cracks called checking in the sidewalls and get a black powder on your fingers/hand when you rub the sidewalls, then all the others here could be right and I would be wrong, but barring that, I say keep on trucking.

Edit: rubbing you hand or fingers across the sidewall will result in a smudge mark, this is not the same as a dry powder residue. Smudge OK, dry powder, get new tires ASAP.

One more edit: You would have had the same experience under the same conditions even if you had brand new tires on the car. Never use cruise in the rain.

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If I experienced what the OP did with old tires I’d replace them now.


On a related note, my spare is now 12 years old. It has never been used and it looks perfect. In fact the only time it has ever left the car has been to change out the battery which is located under it. I’d bet most everyone here is going to say replace it, but it really does look brand new.

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tl;dr have any of the “regulars” here yet mentioned this is generally a dangerous thing to do?

Which really does mean nothing.

I had a set of Pirellis on a car we bought new in 85. Within 3 years they were undriveable in the wet because they were so hard. The car was driven daily and had 25K miles. The tires looked perfect with plenty of tread.

I own a rubber durometer tester. A hardness tester. New tires may read 60 duro. Old tires like my 17 year old spare, tested 85 duro. Looked perfect. Not safe. Was replaced.

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What I typically do when getting new tires is ask the tire shop to put the best old tire onto the spare and recycle the existing spare. This helps to keep the spare reasonably fresh and I don’t intend to use it for anything but getting the car off the road and to a repair shop anyway so not being like new is not a concern.

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Ok, thank you all for the responses, I’ve learned a lot. Now I can start composing a new post about when you all think the new atomic fusion engine for automobiles will be coming out! Aloha!

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One thing for certain, don’t get between the laser’s and the engine … lol …

I obviously commented before reading capri racer’s post. I think skepticism is the proper approach regarding new information. I was skeptical about cold fusion and I was right, I am skeptical about everything Elon Musk says, it all seems calculated and self serving.

There was an article in the Buffalo News warning about roadblocks to buying an electric car. Representatives from “the electric car industry” met with NY Governor Hocul to try to get direct sales to consumers allowed. She seemed cool to the idea. Elon Musk has been campaigning for this for years.

I am also skeptical about controlled fusion that produces more energy that it takes to produce it. It is not that fusion would not do exactly that, I just don’t think that they will beat the control problem with any meaningful amount of matter.

On a practical level, for a limited use vehicle in Hawaii, when replacing your tires you should focus less on the treadwear and more on tire performance.

Performance tires generally wear much faster but offer significanly better "grip/handling " so if you’re replacing the tires by age, the treadware may be unimportant.


Make sure there is air in it otherwise the cracks won’t show up.

My 1960 Chrysler has the same bias ply tires that were on the car in 1975 when i bought it. I wonder what their hardness would test at.

Off the scale!!

Back in the day I thought the 8 y.o. Michelin XZX tires on my 1975 Civic were okay.
They amazingly had decent tread left at nearly 80,000 miles.
Then a dew-dampened road and a panic stop due to a truck running a stop sign caused my little go-cart of a car to swap ends in the blink of an eye.
No collision, but I learned that when it comes to tires, appearance ain’t everything!


Other than having front tires with more traction than the rear, Improperly adjusted brakes cause this! The brakes should have been tested by braking hard in dry, wet, and snowy conditions to make sure this doesn’t happen! A bad proportioning valve can make the rear brakes too strong. Improperly adjusted drum brakes in the rear can too.

Its remarkable to me they still hold air.

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