Dave P, Graham P, other tire chem experts: why do tires turn blue?

[OreoGaborio]

I keep hearing it's "oil coming to the surface" but I know that's bullshit.

So... what's the real reason?


EDIT: Please keep this on topic. I want KNOWLEDGEABLE, FACTUAL, EDUCATIONAL ANSWERS.

[tsorfas]

Not oil I think it's just the chemicals the tire is made out of and the heat brings them out on the surface and cold turns them blue..?
Or something among those lines. It also means nothing on my understanding. Very common on tires stored over winter I guess.

[Imbeek]

And while you are at it (if ok to ask in this thread, might actually be related)...HOW important is age of unused/NOS track tires, assuming good storage? How old is too old at (only) a mid-blue group pace on an sv? 2012 build date pirelli Rossa corsas, use them? How about 2009?

[jasnmar]

Review of antiozonants. - Free Online Library

Antiozonants and antioxidants are added to the rubber to help it keep from breaking down due to oxygen / ozone. It's in all tires (tractor tires, for example Goodyear Tire Blue tint on mud?), but more common to notice "bluing" in tires that experience extreme heat.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is a common additive of this type.

[OreoGaborio]

Review of antiozonants. - Free Online Library

Antiozonants and antioxidants are added to the rubber to help it keep from braking down due to oxygen / ozone. It's in all tires (tractor tires, for example Goodyear Tire Blue tint on mud?), but more common to notice "bluing" in tires that experience extreme heat.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is a common additive of this type.

Well that sure as hell sounds good... Thanks, J. Hopefully someone can confirm?

Is it actually an "oil" as described in that tractor forum thread?

[TheIglu]

It's cuz you aren't using them no mo'. They get sad.

[TheIglu]

But really, look at high grip hard packed clay off-road RC car tracks. Those tracks are known as "blue groove" tracks.

The racing line is full of a blue hard skin. It's basically tire worn into the track. You see the same thing on go-kart tracks. It's about the tire oxidizing or something.

[jasnmar]

Is it actually an "oil" as described in that tractor forum thread?

Is it an oil... I'd say no, but I never studied organic chemistry.

It is a chemical.
It is an organic chemical.
It is "benzenish" or "benzenesque".

I wouldn't call it an "oil" in the classic "petroleum based" meaning of oil (or vegetable or fat based oils).

If we use the uber generic definition of oil as neutral, nonpolarchemical substance, then probably.

[SRTie4k]

The reason the chemical appears blue would be because it absorbs energy in the yellow spectrum.

Color of chemicals - Wikipedia, the free encyclopedia

[butcher bergs]

They were made that way!

[Karaya One]

Review of antiozonants. - Free Online Library

Antiozonants and antioxidants are added to the rubber to help it keep from breaking down due to oxygen / ozone. It's in all tires (tractor tires, for example Goodyear Tire Blue tint on mud?), but more common to notice "bluing" in tires that experience extreme heat.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is a common additive of this type.

This is actually a really good explanation. Bluing is a chemical reaction. We do not see it nearly as much anymore as tire tech advances. We saw a lot of it in older Michelin lines but almost never now. Race tires come with "anti-aging" compounds just like a street tire. What they do not come with is "anti-freezing" tech which street tires have. This is why you always check a race tire for freeze cracks.

As for tire dates - this one subject is perhaps the greatest source of mis-information on the entire planet. Michelin gives ten years in proper storage for tire usage. Out of the sun, in the cool, dry basement. No ozone. I have seen more 5-7 year old race tires do excellent expert lap times with zero effect upon performance. BUT - it's that one guy who insists that race tires MUST be destroyed after 3 months old that people listen to. One thing we have learned - the consumer will NEVER believe the tire engineer. They will always believe the guy on the WERA board who once knew a guy who drove by the Uniroyal factory. Once. We look at 5 years for a race tire as a number we are comfortable with if they have been in our / Michelin's control. If we don't know we say no. We have been sold recently some 2012 motard that have been fantastic tires. Its all about storage. The set of rains stuck in the back of the race trailer for 3 years? They would concern me....

[OreoGaborio]

Does the blueing have anything to do with or is it accelerated by sunlight? I've noticed that being out in the sun seems to increase the blueing effect.

Does this 6PPD chemical react to UV rays or something?

[Karaya One]

Bluing is usually a by-product of excessive heat in the casing. But we do not see it like we used to anymore. And a blued tire will "wear" it off after another session. Its not to my knowledge a sun light issue.

[csmutty]

And while you are at it (if ok to ask in this thread, might actually be related)...HOW important is age of unused/NOS track tires, assuming good storage? How old is too old at (only) a mid-blue group pace on an sv? 2012 build date pirelli Rossa corsas, use them? How about 2009?

I'm using 07 dunlops that have cold cracks and everything on my sv and they still gripped awesome enough to be railing hard in thompson in blue group this year.

[jwm2k3]

Is it an oil... I'd say no, but I never studied organic chemistry.

It is a chemical.
It is an organic chemical.
It is "benzenish" or "benzenesque".

I wouldn't call it an "oil" in the classic "petroleum based" meaning of oil (or vegetable or fat based oils).

If we use the uber generic definition of oil as neutral, nonpolarchemical substance, then probably.

You are a scary dude....scary intelligent. And funny as hell too!

[jasnmar]

Lol. I have decent recall, and am reasonably good at using the Google.

But now I'm off topic. Sorry Pete!