Are these tire cracks just cosmetic?

[rationull]

I know there have been other threads like this in the past (I did a search and read what I could find) but I'm not sure exactly what to think in this case and I figured better safe than sorry. Specifically in one previous post CapriRacer had some concerns about cracks that are close to the wear surface similar to what I'm seeing on my tires.

These are the OEM Dunlop summer tires on my 2011 Subaru. They were manufactured in Japan in July of 2011. They've got 37k miles on them and are wearing what I consider to be very well for OEM tires. I've left the pics relatively large for detail.

I realize that closeup tire photos are generally gonna look pretty ugly but specifically I'm wondering if the cracking on the shoulder is normal. The other threads were enough to convince me that the cracking in the tread grooves isn't a problem. Note the black mark near the bottom of the first pic is NOT a crack -- just the lighting.

Since the tires are only a couple years old, I'm not sure if this is normal. Note it does get pretty cold and pretty hot where we live, so that could be a factor. Like I said, I'm leaning toward "normal" but we've got some trips coming up and I just want to know whether I need to be replacing these soon.

What do you think?

 

[Hollow]

They look a little worse than the Michelin's I have. Purchased mine in December 2010 and they have about 46,000 on them.

 

[tommygunn]

You say it gets cold wher you are.

Are there extended periods of, say, under-40 temps that you drive in?

If you use winter tires, how do you store these summer tires when the snows are in use?

The temperature fluctuation and conditions they're not designed for could be a cause.

But tread cracks aren't anywhere near as bad as sidewall cracks!

 

[actionstan]

Eh... It's always a hard call with tires.. I think tires are typically good for 5 years at least.

I have driven on much much worse, I had hydro edge michilens on my saturn from 2006.. Just replaced this past summer because they were making nervous..

With tires I'd say when in doubt.. Swap em out.. I know this is easier than it sounds not everyone's financial situation is that easy(I know mine isn't). So IMO it's ultimately up to you... I think they look ok, those cracks aren't too deep, but if it makes you un-easy and you doubt them there is only one way to fix that..

 

[dparm]

I wonder if they were autocrossed or raced on.

 

[Rand]

thats perfectly normal.

2 year old nokian wrg2's are worse.

 

[salv]

Here in NY, we can fail a vehicle on inspection for weather cracking like what you have.
In the last picture, the tread depth is very low. I would recommend tire replacement soon.

 

[Papa Bear]

Treadwear 280 !! Geez, they were half worn out before they left the factory ....

cracks look cosmetic

 

[Kuato]

Noting to worry about, IMO. But looks like they may have been a little overinflated, with most of the wear in the center and not much on the shoulders.

 

[rationull]

Originally Posted By: tommygunn
You say it gets cold wher you are.

Are there extended periods of, say, under-40 temps that you drive in?


I'm sorry -- I don't really have the right to say it gets cold here

The lows this last week were in the upper teens, and that's basically as cold as it gets around here and is not really normal. It usually only gets down to low 30s/high 20s at a stretch, and that's the overnight lows (when the car is in the garage). No snow, I don't have winter tires.

Originally Posted By: salv
Here in NY, we can fail a vehicle on inspection for weather cracking like what you have.
In the last picture, the tread depth is very low. I would recommend tire replacement soon.


That's just the picture. The stripes of tread in the middle of the picture had extremely shallow sipes and they are worn off, but they've still got 5/32" of tread depth. How long does it take for tires to crack like that in NY?

Originally Posted By: dparm
I wonder if they were autocrossed or raced on.


Nope. Spirited driving but no track or autocross time.

 

[rationull]

Originally Posted By: Kuato
Noting to worry about, IMO. But looks like they may have been a little overinflated, with most of the wear in the center and not much on the shoulders.


I run them a few PSI high. Placard recommendation is 33 front, 32 rear and I tend to run 35 front, 34 rear or so. The tread depth is actually pretty even between the sides and the middle when measured -- I think it looks that way because of which half of the tire I got in the pics, and the sipe patterns on those pieces (or lack of sipe patterns as the case may be). These are Dunlop SP Sport 01s and they have an asymmetric pattern with more siping on the inside.

 

[JHZR2]

Ive seen much worse in still servicable tires. I am one to condemn tires early for cracking, but I would be comfortable driving on those.

 

[KB2008X]

Those "cracks" are nothing to worry about. Just try to find tires that are two years and a few months old and with 37,000 miles on them that don't show similar cracking.

I would keep a close eye on the tread depth though. 5/32" is getting pretty thin, and the wet traction and resistance to hydroplaning will suffer. I'd start to look around for tires. 40,000 miles on tires with a 280 treadwear rating is doing pretty good. You've gotten your money's worth out of them.

Tires are the most important piece of safety equipment on a vehicle.

 

[rationull]

Yes, I do agree I've gotten my money's worth. I'm guessing these will last me another 6 months or so, and I have already started to consider what will replace them.

Ironically these tires have lasted better than the OEM tires on either of the two new economy cars my wife and I have had, despite the fact that they're 280 treadwear summer tires.


Thanks, all. I will rest easy for now about the cracks. I don't know why I haven't noticed them in previous cars but I must've just not been looking closely enough.

 

[The_Jeff]

cosmetic

 

[CapriRacer]

I would say you are getting close to the time to remove those tires, but still have some time. We might be talking 6 months.

On the other hand, it is colder now and the cracking MIGHT not get very much worse over the course of the cold weather.

I would recommend you keep an eye out on them. Post back if the situation gets worse.

 

[BMWTurboDzl]

Looks okay. I was told years ago that any tire over 4 yrs old should be scrapped because the rubber has dried to a point where a blow out is more likely.

 

[rslifkin]

Originally Posted By: CapriRacer
On the other hand, it is colder now and the cracking MIGHT not get very much worse over the course of the cold weather.


Wouldn't the summer compound hardening in the cold make the tires more likely to crack due to reduced flexibility?

 

[CapriRacer]

Originally Posted By: rslifkin
Wouldn't the summer compound hardening in the cold make the tires more likely to crack due to reduced flexibility?


It depends - and to explain why I need to fill you in on some fundamentals.

First , some types of rubber have glass transition temperatures that are experienced in winter. OK, now I have to explain what a "glass transition" is.

I know we were all taught that things come in 3 states: Solid, liquid, and gas. Unfortunately, that is not exactly correct. There are states of matter that are different. Glass, for example, exhibits properties of both a solid and a liquid at the same time.

Rubber is kind of like that. - AND - it changes the way it behaves based on temperature. Rubber transitions from a flexible, elastic material to a brittle material at certain temperatures, and that temperature varies according to the type of rubber used - and since tires are mixtures of rubber, you can get all kinds of different responses to temperature.

The second thing has to do with the rate of oxidation - which obviously slows down with temperature.

So on the one side is the change in material properties, and on the other is the rate of deterioration.

It's hard to say what affect temperature is going to have on a tire without knowing a lot more about both the tire and the environment it is operating in.

Note to the curious: Look up "Amorphous Solid" for more details.

 

[rationull]

CapriRacer -- I just wanted to thank you for you incredibly informative posts in the tire section. No offense meant to anyone else but I always look for your name in particular in this sub-forum.