Tires turning blue?

FrancisChan · **Posted:** Mon Jun 29, 2015 4:36 pm

Oppy mentioned that my tires appeared to be turning a little bluish on the sidewalls. Is this a bad thing or just a sign that they're getting heat cycled?

They're Dunlop Z2 Star Specs by the way and have only been on the car for 3 months daily driven and 6 autocross events

Chad Culbertson · **Posted:** Mon Jun 29, 2015 5:21 pm

I've noticed this before on my motorcycle tires after they've been under a cover in the sun light and the cover has heated the tires up in some places pretty good.

It didn't seem to cause any issues.

steve remchak · **Posted:** Mon Jun 29, 2015 8:38 pm

Might want to check your alignment & air pressures.... blue is heat related. As in too much.

FrancisChan · **Posted:** Mon Jun 29, 2015 9:18 pm

The tire temps seemed to be ok this past weekend. But I do remember them getting rather hot to the touch the event before that.

Is it just going to kill the longevity before they loose grip?

steve remchak · **Posted:** Mon Jun 29, 2015 9:39 pm

I'm no expert but I believe blue is hardening of the compound.

FrancisChan · **Posted:** Tue Jun 30, 2015 11:09 am

Oh well, I guess that means more road mileage.

RobLupella · **Posted:** Tue Jun 30, 2015 6:46 pm

I am an expert on blue tires. I at first thought it was cool since they matched the color of my car. j/k

Actually once they turn blue they are generally getting past their optimal grip and will be usable but you will find less grip.

JasonWatts · **Posted:** Wed Jul 01, 2015 12:22 am

The way it was told to me in relation to motorcycle tires is that once they blue it means they were overheated. Because of this I have heard the grip can be less predictable, usually at its limits.

This of course is what I have heard. Never read to much into it, but I dont trust a blued tire and will never mount one... Then again I dont usually mount other peoples old tires and have never blued one of my own motorcycle tires. Car tires I dont care, just makes it more fun to drive hard.

DickRasmussen · **Posted:** Wed Jul 01, 2015 7:06 am

FrancisChan wrote:

Oppy mentioned that my tires appeared to be turning a little bluish on the sidewalls. Is this a bad thing or just a sign that they're getting heat cycled?

They're Dunlop Z2 Star Specs by the way and have only been on the car for 3 months daily driven and 6 autocross events

Can you post a picture of the blue area(s)?

I've had old race and "R compound" street tires develop a blue tint on more highly stressed portions of the actual tread but haven't seen it on sidewalls or with new tires like yours. My "not" Star Spec ZII's last year didn't turn blue when I owned them but Art has the second set so maybe he can comment.

That said, assuming plenty of tread remaining any blue or "crustiness" on the actual tread will be long gone after the first run at almost any site.

Chad Culbertson · **Posted:** Wed Jul 01, 2015 9:52 am

My motorcycle tires looked like there were just a few places close to the sidewall where the black cover had gotten hot from the sun and transferred some heat to the tire. Hopefully it didn't really damage it, the cover was a stop gap until I got a building to park them in at the new place.

I haven't noticed any change in handling and it went away very quickly anyway. I also haven't been dragging knee around any corners lately, lol.

FrancisChan · **Posted:** Wed Jul 01, 2015 11:41 am

DickRasmussen wrote:

FrancisChan wrote:

Oppy mentioned that my tires appeared to be turning a little bluish on the sidewalls. Is this a bad thing or just a sign that they're getting heat cycled?

They're Dunlop Z2 Star Specs by the way and have only been on the car for 3 months daily driven and 6 autocross events

Can you post a picture of the blue area(s)?

I've had old race and "R compound" street tires develop a blue tint on more highly stressed portions of the actual tread but haven't seen it on sidewalls or with new tires like yours. My "not" Star Spec ZII's last year didn't turn blue when I owned them but Art has the second set so maybe he can comment.

That said, assuming plenty of tread remaining any blue or "crustiness" on the actual tread will be long gone after the first run at almost any site.

I'll try and get some pictures up, it's mostly on the side wall up near the tread. They were already brown, but I'm lead to believe that's due to UV protectants in the rubber.

To throw another variable in the works, the car is parked outside the whole time and is out in the sun at the park n' ride lot during the day.

If it's not going to effect my everyday safety I'll ignore it and take note for next season's tires. They are still plenty grippy for on ramps.

Arthur McDonald · **Joined:** Fri Aug 29, 2003 1:54 am **Posts:** 2052

I was always told that your tires turned blue because you were holding your breath during your autocross runs.

FrancisChan · **Posted:** Thu Jul 02, 2015 8:20 am

No wonder I was getting light headed!

Picture as promised. It's almost like a blue ring on the sidewall.

DickRasmussen · **Posted:** Thu Jul 02, 2015 9:55 pm

I don't see anything to be concerned about. I see a faint "blue" tint about half way between the edge of the tread and the rim in the relatively small font word area . Is that what you mean?

Or do you mean the scuffed area adjacent to the tread?

I don't see an issue in either location.

Bernie Baake · **Posted:** Thu Jul 02, 2015 10:33 pm

Tires turning blue is a function of the oils that are used in the manufacture of the tire. Oils are used to keep the tire supple and pliable through out its life. The oils tend to migrate to the surface when the tire is heated, as in spirited driving on autocross or track.....or if you hotrod around town. It in itself is not degrading the tire, the heat cycling is degrading the performance and the bluing of the tire is an indication that you've heat cycled your rubber.

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