[cbodie]

05 LL Bean 86K.
I was cleaning the wheel well on the rear passenger when my hand happened to feel the wires from the tire. After taking the wheel off, I found the spot on the attachment. There's only one wear spot like this, and the rest of the tire looks OK.
I would like to mention that the rear has been a little "shakey" the last 700 miles or so. I thought it was mud on the wheel, affecting the balance.
So, I rotated all other tires, front to back, and put the dummy on the front passenger for the time being. (That tire looks like a catastrophic failure waiting to happen.)
These are Nitto NT850 225 55 R17. Looks like stock size. I'd like to replace the one tire.
Should I:
a) Replace the tire with the EXACT size and brand. (I find this to low risk, but I'd like to start walking away from the Nittos.)
b) Replace it with another brand, same size and basic wheel characteristics? (This is a back-up plan in case I can't find the EXACT Nitto.)

What caused this? Is this some kind of alignment issue in the back? Maybe a scrape or cut from a long time ago, now the damage has progressed?
Work has caused me to log 250+ mile days 2-4 times a week in addition to the 40 mile to and from normal work commute.

 

[1 Lucky Texan]

now's a good time to get 4 new tires. No shaving, no shopping for a used tire, no worries about torque bind.

and no Nittos I guess (though, just about any brand could have a bad tire on occasion, some are made with quite a bit of human labor, for example watch this; http://youtu.be/raBVyM4aJ5M?t=3m39s

so, if final inspection slips up, a low quality tire might make it to market i guess. )

 

[plain OM]

Go with new set of tires, and have a 4 wheel alignment done, along with a full inspection of the suspension.

If I'm interpreting the photo correctly, that tire is worn down to the tread wear limit -- the bars are showing on the grooves across the full surface. This also suggests that the other tires are worn down to, or close to the limit, meaning time to replace.

Moreover, not mixing the old worn tires with a new tire will help avoid potential damage to the drive train (the reference to "torque bind" above). Subaru's require that the circumference (not diameter or radius) of all four tires be within 1/4-inch. A difference of just 1.3/32 of an inch in tread depth on otherwise identical tires would result in that 1/4-inch difference in circumference. Mixing old and new tires, or different brands/models, might work, but it's not going to be good if you don't want to risk other problems.

 

[Wagondude]

I thought I was the only one that would drive a set of tires till you could see the air. I'd say you got your moneys' worth out of them. Pony up for a new set.

 

[cbodie]

These tires have 46K on them. Left side looks great. Right rear had the one mark attached, and the right front has crowning on the outside. Left side looks GREAT!
(You'd think I was stock car racin' or something.)

plain OM: you're right. I need new shocks for the rear for sure, and I'd like to go ahead and put a thicker torsion bar on for the heck of it. That's the only mod I'm considering just to loosen up the rear. Since I didn't purchase the tires, Nitto is going to wash their hands of any warranty according to the warranty documentation I saw on the website. I've looked at the threads on this forum for tires, and basically narrowed it down to a few. The Nittos were a little loud, though I haven't had 17's with such a low profile before so my comparisons might be skewed. Since I have no snow to speak of I don't need winter tires. The Nittos along with the really good AWD have provided sufficient traction in mud and dirt I experience on occasion with my job. The car won't see light track days like my previous vehicle. Didn't really feel any tire "roll" but that might be due to low profile also.

Geez, could this come at a better time?! X-mas spending and now I'm rolling on a doughnut!

 

[idosubaru]

it's benign - you can get whatever brand tire you want, just make sure it's the right size. unbelievable amounts of people run different make tires. be smart or listen to folks that do this all the time and you're golden.

the idea of running a different make tire or tread pattern that's the exact same size being an issue is one of the more ignorant things i see posted all the time online. it's untrue and holds no water at all. that being said - it ***is*** a great approach to replace as a set of 4. but i also know people that's not a good fit for and as such it's not hard to replace less than all 4 tires.

shops in Subaru rich areas will replace two tires at a time and put them on opposite side front/rear - this works on Subaru's. i don't recommend it and i don't do it - but it does work based on the way the AWD system, transaxle and differentials work.

that also means some significant things about running tires but i'm not going to get all technical.

you have two choices - make informed intelligent decisions that fit your situation or go the one size fits all approach of replacing them all. both work just fine.

get a used tire, sometimes ebay even has some. a used tire will certainly match your others closer than a used tire.

more tread put on the front and they'll wear down to match the rears.

another option - buy two new ones to replace the rights and put the other two on the rear. or buy one new one and put the best two up front.

 

[idosubaru]

i saw an Outback wear a rear tire like that - it was the rear strut. i believe it gets weak and allows the tire to "slide" against the road surface instead of pushing down firmly on it...or that's my impression. either way taking the thing apart and replacing the strut fixed that.

some options to limp it along:
get a used strut at the very least to keep your new tire from wearing like that. i generally would replace new but they're not really worth anything used so should be easy to score an assembly and they are super easy to swap out. 2 nuts up top and one bolt on the bottom - bam, done.

if you can't afford struts - then put your worst tire on that same location so you're not prematurely wearing a good tire.

and replace one strut if you have too, it's not a big deal. i generally replace in sets but also realize that's not always a great option and know that it doesn't really matter. i do it for other reasons. people say you gotta replace in pairs, i'm not sure what to say about that concept except that it's another weak one-size-fits-all generality that fails in all sorts of ways. you got a bad strut wearing a tire...replace that one strut if you have too.

it could be a bad tire, but i doubt it. i wouldn't blame them for wavering to cover that under warranty.

 

[plain OM]

it's benign - you can get whatever brand tire you want, just make sure it's the right size. . . . .
the idea of running a different make tire or tread pattern that's the exact same size being an issue is one of the more ignorant things i see posted all the time online. it's untrue and holds no water at all.. . . .make informed intelligent decisions

I'm with you on making informed decisions.

So let's look at what Subaru says:

". . .all 4 tires should be within approximately ¼" of each other in circumference when measured at the center of the tread."

[Source: Subaru of America, TechTips, December 2010. Also see: http://www.subaruoutback.org/forums...ec-confirmed-subaru-techtips.html#post294007]]

Granted, this says nothing about brand. But the Owners Manual does. I don't have the 2005 OM, but my 07 Owners Manual says:

All four tires must be the same in terms of manufacturer, brand (tread pattern), construction, degree of wear, speed symbol, load index and size. Mixing tires of different types, sizes or degrees of wear can result in damage to the vehicle’s power train.

[Source, 2007 Subaru Outback Owners Manual, Maintenance and service section, page 11-40.]

Finally, let's look at tire specs from tire company websites or catalogs, all 225/55/17:

The original factory-supplied Bridgestone Potenza RE92's have an overall diameter (unloaded) of 26.9 inches, and turns 775 revolutions per mile. This rpm equates to a rolling circumference of 81.75 inches.

Based on reading posts here, the Goodyear Assurance Triple Tred has been popular for 3rd Gen. Outbacks. That tire has an overall diameter of 26.8 inches, and turns 780 revolutions per mile, which equates to a rolling circumference of 81.23 inches.

The Michelin Primacy MXV4 is another well-received tire. It has an overall diameter of 26.8 inches, and turns 778 revolutions per mile, for a rolling circumference of 81.44 inches.

According to Tire Rack, the Kumho Ecsta 4X is a popular seller for the 2005 LLBean. It has an overall diameter of 26.8 inches, and turns 775 revolutions per mile, for a rolling circumference of 81.75 inches, the same as the factory Bridgestones.

As is apparent, different tires of the same nominal size have different diameters and different rolling circumferences. In these examples, the difference in rolling circumference is as much as a full half-inch, which is well above the 1/4-inch Subaru recommendation.

You can check other tire company websites to find similar specifications, and I can assure you that more often than not, they will exhibit differences, not only in the circumference, but in other specifications such as load and speed ratings, which will also affect how they perform.

I will add that other AWD car makers have recommended limits on the difference in circumference of the four tires; the figure might vary but the concept is the same. Tire Rack has several articles about the need to have the same tires all around. Here's one: Replacing One Tire on an AWD Vehicle - Todd's tire decision guide | Tire Rack.

I have read in this forum that some have used mixed tires and have not reported experiencing any negative effects. That may very well be the case. Then again, we've seen posts where the AWD system, or a drive train component, has failed, and the tires are found to have significant differences. Or where there have been AWD problem-related symptoms that were corrected by replacing the existing odd set of tires. Granted, there's no direct evidence that one caused the other, but there must be a reason AWD car makers have limits on tire circumference differences, and as noted in the TechTips reference above, Subaru does link tire circumference differences to power train damage.

Certainly, read in these forums what others do or have done, but also learn what the manufacturer of your car and the makers of the tires you might use have to say about their products. Then make an "informed" decision.

 

[cbodie]

i saw an Outback wear a rear tire like that - it was the rear strut. i believe it gets weak and allows the tire to "slide" against the road surface instead of pushing down firmly on it...or that's my impression. either way taking the thing apart and replacing the strut fixed that.

GREAT ADVICE all around, plain OM! :29:

I KNOW for a fact the rear struts are bad. . .saw the back end boucing as I followed the previous owner.

I've got KYB rears (both) spec'd for 2005 OB's coming, and I'm replacing the mounting brackets too. All for about $160 delivered to the house. Today I'm shopping for (4) Primacy MXV4 tires. Planning ahead, I'm starting fresh with the MXV4's and if they're quieter and perform well, I'll manage future tire issues accordingly. (I expect they'll be rather impressive compared to the Nittos.) The way our family budget works, I'll be keeping this car for 10 years. So this level of commitment is warranted at this time, IMO.

Alignment after struts and tires installed.

 

[idosubaru]

I agree most people should follow Subaru. Subaru is certainly the best place to start for folks who can't or don't have significant experience, time, or resources to rely on.

None of this seems to matter for this post but to qualify. Each person will find a different fit and approach to maintenance and suggestions, boards like this are a great place to bring it all out.

I did qualify each option and those are terrible "one-size-fits-all" approaches, no doubt so they need to be qualified and questioned and utilized properly. I've worked with folks who simply can't do 4 tires and a one-size-fits-all approach isn't a good fit. They should know they have options that have zero risk (everything else being equal - which it never is - folks with perfect maintenance have anecdotal trans failures). The option for many folks in that situation is to just ignore it and not get tires at all...wait til that bad tire blows up - a worse choice than my options listed above - and i've seen it done, this year even.

Subaru's timing belt, headgasket, and other maintenance statements are better seen as suggestions and not the best long term value adding approach to maintenance for folks wanting 300,000 miles out of their vehicles like I do. Individuals, engine rebuilders, All Wheel Drive Auto in Seattle and tons of other Subaru hobbyist and independents know this. Many folks proficient with Subarus, have found better-than-Subaru maintenance procedures for other components as well over the decades. That comes with experience, resources (like forums) and quantity. Subaru is a great start but not the end of the discussion. The manuals also say to take the car into Subaru dealers for certain items, but forums like this are not necessarily meant to enforce Subaru rigidity and many folks don't follow those sentences in the owners manual.

With all the opinions, some of it borrowed from other makes or time periods or anecdotal inexperienced cubicle discussions, many folks with little experience commenting or regurgitated from other websites, it's hard to discern all the information. But in the end I love forums and their ability to teach.

 

[cbodie]

Another 10 years with this car, and 15k miles/year, It'll be around 236,000 when I'm ready to sell. It'll be 17 years old, and so will my oldest child. Hmmmmm, so maybe I won't sell and let them use the 'ru as their first car.

Michelin MXV4's are super quiet. Car feels a little better too. They don't seem as aggressive as the Nitto's, and from the first couple miles pushing it into my usual turns, I suspect they'll slide and maybe roll a little more. This is a first impression with very low miles to establish.