Edges of Tread

[HowAboutThis]

17 Forester. I posted about this last winter and my alignment is supposedly in spec. Someone said it's a Subaru thing. Tire shop thought it was interesting, too, but said stuff looked fine. I'm going to take to the dealer this summer. Basically the inner and outer edges of all 4 tires have a pinkie width area where the siping is like melted together or gone basically. So it's smooth. You can see faintly where the siping was. Tire shop mentioned low air pressure and I side nope, I check at least twice per month and run them at 35 which is more than the door placard. They recommended the dealer and said maybe Subaru has more knowledge but it's not common from what they see and suspension and alignment seemed ok to them. Any ideas? Don't have the car near me now but I'll try to post pics again later.

Edit: the OE Yokohamas went 75k miles with 4/32nds left across the entire tire but the same oddity on the outer edges. The tread isn't any less, so to speak, but it's just smooth and the siping is destroyed or smoothed out like a pinkie width wide about a pinkie width from the inner and outer edges.

 

[Lubener]

Pics?

 

[eljefino]

Siping doesn't always go all the way down. Tires look worse as they age-- "simpler."

 

[HowAboutThis]

You can see that thin ring. These have about 35k miles on them rotated every 6-7k. Commute is mostly highway. It's inner and outer like that on all 4. All 4 are equal wear. Still have 9/32nds across the rest of tread on all 4 tires.

 

[HowAboutThis]

Siping doesn't always go all the way down. Tires look worse as they age-- "simpler."

That's what I'm wondering. But I have the Defender on my Corolla, too. Bought them 4 months before these for my wife's car and they don't look like that and have almost exactly the same miles on them.

 

[HowAboutThis]

Here's a link to a pic of the tread and my Corolla still has the siping to the edge.

https://www.tirerack.com/tires/michelin-defender-t-plus-h

 

[Danno]

Check a new tire and see how far down the siping goes. It may only be 2/32nds in that area with a hidden rib, to improve cornering feel, with less squirm.

 

[HowAboutThis]

Check a new tire and see how far down the siping goes. It may only be 2/32nds in that area with a hidden rib, to improve cornering feel, with less squirm.

If you look at the Tire Rack picture (and when I look at the same tire on my Corolla), it doesn't seem like this is the case.

 

[jhellwig]

If the siping went all the way down on the lug the tire would wear odd or fall apart. Kinda like a mud tire.

 

[HowAboutThis]

If the siping went all the way down on the lug the tire would wear odd or fall apart. Kinda like a mud tire.

So you think it's normal for these tires and no concern? It's exactly the same on all 4. Tread depth perfect across all 4 as well.

 

[jhellwig]

So you think it's normal for these tires and no concern? It's exactly the same on all 4. Tread depth perfect across all 4 as well.

Every tire I have seen has that same ridge in the siping on the edges.

 

[HowAboutThis]

Delete. Pic didn't upload.

 

[HowAboutThis]

Every tire I have seen has that same ridge in the siping on the edges.

I can't get the pic to upload. Website is being odd. I'm not talking where my finger is. Look about a finger's width onto the tread. There's a spot where the siping is like welded closed and it didn't use to be that way. Just called Subaru and they said all their digital alignment checks during inspections have shown the car is aligned fine.

 

[HowAboutThis]

@jhellwig

 

[HowAboutThis]

@jhellwig and it's on EVERY tire inner and outer in the EXACT same location like that. Why is the siping getting smushed like that? Same tires on my car (the pics are my wife's car) with same mileage and my sipes aren't smushed closed like that.

 

[jhellwig]

Because not all tire molds are the same. Every tire brand does that for the most part.

 

[CapriRacer]

@jhellwig and it's on EVERY tire inner and outer in the EXACT same location like that. Why is the siping getting smushed like that? Same tires on my car (the pics are my wife's car) with same mileage and my sipes aren't smushed closed like that.

Howie (may I call you by your first name?),

I hope you realize that sipes don't have to be the same depth. Not only can there be sipes of different depths, but within the same sipe, different parts of the sipe can have different depths.

In your photos there is a groove at an angle just outside the yellow area that is quite clearly not the same depth as grooves and sipes around it. Why are you not commenting on that?

Also, it is known that tire manufacturers don't always have the exact same tread pattern throughout the entire size line up. The tire manufacturer I used to work for had - at one point in time - 5 different tires in the same size and the same name on the sidewall that they supplied to 5 different car manufacturers. Several of those looked different when new, but some had differences that didn't become apparent until the tires wore a little - and some were exactly the same except for the tread rubber.

I can easily imagine that a tire manufacturer could notice some peculiar wear pattern that comes on vehicles with certain types of suspensions, so they change certain sizes that fit onto those, but leave the rest of the lineup alone. I don't know that that is what is going on here, but it's possible.

 

[meep]

Great posts. this is not an alignment problem, and not a tire problem. Yes it does catch the eye because this lands in the perfect location for cornering wear and edge wear. More siping gives more wet grip (to a point). But more siping also destabilizes tread blocks. So the tire companies have to make decisions and compromises and how much, how deep, siping goes, and in this case, they don’t have siping there to preserve tread strength. Those sipes will likely continue to shrink with age, as they are probably like an upside-down triangle cut into the tread, not vertically-cut.

 

[HowAboutThis]

Great posts. this is not an alignment problem, and not a tire problem. Yes it does catch the eye because this lands in the perfect location for cornering wear and edge wear. More siping gives more wet grip (to a point). But more siping also destabilizes tread blocks. So the tire companies have to make decisions and compromises and how much, how deep, siping goes, and in this case, they don’t have siping there to preserve tread strength. Those sipes will likely continue to shrink with age, as they are probably like an upside-down triangle cut into the tread, not vertically-cut.

Discount Tire guy said the sipes often close like this and reopen as the tires wear. So I'll wait to see what the alignment looks like too. He said something about 3D sipes being jagged like Z's on Michelin? Who knows.

 

[Nick1994]

I'd just chalk it up as being interesting and move on. It isn't affecting your drive-ability, safety, or even tread life. Even if it is affecting treadlife, over the whole life of the tires you're maybe coming up $5 short. Factoring in parts or an alignment to try to cure something isn't going to even come close in paying for itself.

After this set wears out, try a different brand of tire.