CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

What is this ring around both my tires?

,

I have just recently purchased two new front tyres for my car, Michelin Pilot Sport 4S (Build date late 2019).

(I think) ever since new or very soon after, I’ve noticed a worn black identical ring around the sidewall on both of them. When freshly washed it looks black, and when unwashed it develops a powdery like substance that can be wiped away.

Does anyone have any clue? Thank you !

Nice tires! Good photos! Great description!
That’s interesting and I could only hazard a guess, but perhaps @CapriRacer, a tire expert who frequents this site could offer a helpful explanation.

He maintains a website, http://barrystiretech.com/index.html
and I believe he can be contacted there, but it wouldn’t surprise me if pulls up here soonimage
CSA
:palm_tree: :sunglasses: :palm_tree:

Are they stock size?

That looks like where the tires were touching something when they were stacked - probably the neighboring tire. The black is the oil in the rubber matrix and the white is the antioxidant also embedded in the rubber matrix. Nothing to worry about. Eventually both will go away.

2 Likes

Thanks for your reply, this is good to hear. Even if I try clean off the black, it won’t come off. Will it still go away by itself eventually?

Yes stock size

Yes. Right now there is an excess, and that will dissipate over time.

@CapriRacer Capri . in the persons first post they say 2 new front tyres . They must not be in the US but I thought it was recommended every where to put 2 only new tires on the rear of a vehicle. Should they be told to have them put on the rear .

1 Like

Yup, The recommendation doesn’t know international borders.

Good catch!

1 Like

My car has a staggered set up. 275/35/19 rear, 255/35/19 front.

I am surprised that the tire shop did not almost insist 4 new tires be mounted . It might be a safe move to plan on new tires for the rear soon. You should find a video on the Michelin web site showing what can happen with new tire on the front.

I have brand new rear tires as well. I did not mention that because my concern with this post is only with the front tires

1 Like

My first thought would be underinflated. Check the pressure with a known accurate gauge.

Did you not read CapriRacer posts . He is an actual tire expert .

Looks like the lubricant some tire shops use when mounting tires…