tires once again

[tahoe healey]

We purchased Michlens for my wife's 4Runner today and the store mgr said they have a UV protector on the rubber. He said not to scrub hard (as in commercial car wash) or it will be removed eventually. And not to use things like Armoral or the UV will crack the side wall. He also said the NDOT date is a mfg date and not the start of a clock. He said 5 to 6 years of use is what is expected. Not 5 to 6 years from the mfg date (longer if stored out of the sun).
Was he just blowing air in my tires? I'm not worried about the 4Runner but the Healey. Some of you may remember that my "new" Michlens had a two year old mfg date but I had waited months to get them.
Thoughts?

 

[Keoke]

HI TH, No I do not think the store Mgr was too far off the mark. Most of the rubber parts we purchase for the Healeys too have the UV protectant on them it looks like a whitish powder and because it is so unatractive we scrub it off to get that newish black look. As for Armoral it has been widely circulated in the past that it causes rubber/Vynl etc to crack.On the other hand, newer products like 303 ,2002,Lexol Etc, do not seem to cause any defects in the materials and actually appear to prolong their life.---Fwiw---Keoke

 

[Dave Russell]

[ QUOTE ]
We purchased Michlens for my wife's 4Runner today and the store mgr said they have a UV protector on the rubber. He said not to scrub hard (as in commercial car wash) or it will be removed eventually. And not to use things like Armoral or the UV will crack the side wall. He also said the NDOT date is a mfg date and not the start of a clock. He said 5 to 6 years of use is what is expected. Not 5 to 6 years from the mfg date (longer if stored out of the sun).


[/ QUOTE ]
Hi TH,
There is little doubt that the tire aging process starts as soon as they are manufactured & IS "the start of a clock". No hard & fast rule exists for acceptable tire age. Tread hardening, & tread separation are the most common problems associated with aging. This hardening is actually a much slower extension of the original vulcanizing process which is used to harden the soft green rubber to it's intended hardness.

How long it takes to harden a tire to unsatisfactory traction or safety levels, depends on temperature, amount of ozone exposure, & amount of ultraviolet exposure, both during storage & during use. A tire that is stored in hot, humid conditions & exposed to sunlight will age nearly as fast as if it is on the car, if not faster. A tire that is stored in cool, dry, & dark conditions may age much more slowly.

Skipping over the tread separation safety issue, although several European car manufacturers recommend a tire age limit of around six years, & Ford & Chrysler have recently adopted a maximum tire age recommendation of around six years, tires can have a significant loss of traction as they age & harden.

I recently had to temporarily reinstall my 10 year old tires which measure 80 on a "Shore A Scale" durometer. The relatively new Michelins Measured 60 on the same scale. The loss of traction when cornering was very obvious with the harder tires. To put the Shore A Scale in perspective, my thumb nail measures 97, the underside of my thumb measures 50.

As an aside, I replaced the 175-15 Michelins with Gillette WT 165-15. They were manufactured March 2005 & also measure 60 on the Shore A scale, but that is another story.

The "UV protector" is actually the mold release compound that is used to keep the tire from sticking in the mold when it is vulcanized. It may have "some" UV protection value but was not intended for this purpose & looks pretty tacky.
D