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OT--AWD and a single new tire?
 

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/10/13 2:08 PM

OT--AWD and a single new tire?

I had to replace one of the tires on my car due to some pot hole... Insurance covers it.

I vaguely recall some talk that on AWD cars, all tires need to be changed when one is changed. Otherwise it would mess up the AWD mech. Is there truth to that?

And if so, how important it that? Basically, if that needs to be done, it needs to be justified to the insurance company.

(the other tires are nowhere near new...)

I figure this forum of very technical group might know the REAL answer! :D

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KerryIrons
Joined: 12 Jan 2004
Posts: 3234
Location: Midland, MI

7/10/13 7:09 PM

How worn?

There are specs that tell you how much wear on a tire set you can have before you have to replace them all. The idea is that with different size tires, the AWD will always be out of synch and risk damage. We had this happen and decided not to take chances (we heard the same story from two different tire stores and it was confirmed in discussions here). A tire store will be able to explain this, and the car manufacturer is the one who sets the specs. Your insurance agent should be well-aware of this.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/10/13 10:46 PM

We where told 4mm max tread depth diff on our Equinox AWD. The Michelin tires had just over 1/2 tread left @ 45k [amazing in itself] and FrntRt got a sidewall cut. So we needed 4 tires. Also ready for brake we figured. But GM making the dealer take it back and give us a new one solved all that for us. The new one had 7 miles on everything.

I do not know what other brands might specify as max wear difference. But 4mm seems a very tight standard to us.

If that is any help I dunno.

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Craig
Joined: 12 Jan 2004
Posts: 591

7/11/13 2:01 AM

The issues are real, running one new tire in a group of used ones will wreak havoc with your AWD vehicle. You'll even find that some insurance companies will void your policy if you get into an accident if you've got mismatched tires on an AWD vehicle. You'd be smart to rotate a 5th tire into the mix when starting from new. If you never have a problem you'll get 25% more life out of your set up and if you do have an issue you'll have an equally worn 5th wheel to throw into the mix. The odds of you having two problems are very slight.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/11/13 5:22 AM

Sounds like another good reason...

...not to buy an AWD vehicle unless one actually needs it.

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walter
Joined: 11 Jan 2004
Posts: 4391
Location: metro-motown-area

7/11/13 6:23 AM

for more worn situations, change out the matching tyre

excessive AWD would occur when tire diameters are mis-matched at the same end of the vehicle (i.e., new on left-front, worn on right front).

AWD systems are designed to deal with moderate diameter differences from front-rear of a car. it's relatively common practice for cars of a sporting nature to have staggered rims/tires with wider donuts in back. OEMs make efforts to match up the tire diameter for staggered setups, but it's impossible to get them exactly in sync when using different tire specs and modern AWD systems have enough slip designed in to deal with these normal moderate differences.

so if you're paranoid, buy replacement tires in pairs and fit them up at the same end of the car.

honestly i think it's an old wive's tale, as even for left/right difference modern cars have differentials that deal with the different distances covered by your wheels with every left or right turn you make! this was more of a problem back in the old-school 4WD days when the front and rear drive systems were locked together and were only supposed to be activated by the driver when conditions merited (i.e., snow, mud, offroad). modern AWD systems are nothing like the old-school 4WD systems.

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Wheels
Joined: 11 Jan 2004
Posts: 1160
Location: Needham, MA

7/11/13 7:26 AM

This is correct.


quote:
so if you're paranoid, buy replacement tires in pairs and fit them up at the same end of the car.


Wheels

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/11/13 7:59 AM


quote:
so if you're paranoid, buy replacement tires in pairs and fit them up at the same end of the car.

I'm not paranoid.

That is, if there's indeed such a requirement from the manufacturer as suggested by Brian (perhaps differ by design of the AWD mech?), I would present it to the adjuster. And I expect him to give me a good reason why it won't be covered.

But if as the man from Detroit said, it's more an old wife's tale, I won't get all upset when the adjuster say no.

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

7/11/13 8:52 AM

--honestly i think it's an old wive's tale,
--some insurance companies will void your policy if you get into an accident if you've got mismatched tires on an AWD vehicle

I'm willing to bet both of these statements are true. There are so many variables and collected experience conspires against the consumer. i.e. question authority (until your time, patience or money runs out.)

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walter
Joined: 11 Jan 2004
Posts: 4391
Location: metro-motown-area

7/11/13 9:17 AM

i bet the rules/caveats are in place for outliers, extremes

as long as you're not mixing a brand-new tire with an almost-bald tire, i doubt anyone would notice enough to even think about disqualify a claim.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/11/13 9:34 AM

I had sourced an exact used replacement on eBay with the tread wear in spec for reasonable price FWIW.
Other choice was to sell the 1/2 worn Michelins after a new set of sneakers. I thought the 3 would bring premium price and just toss in the cut one with a AS IS disclaimer signed disclosing the cut. I thought $300 for the 4 was probable being Michelins and a common size. But the dealer as I said can worry about it now.

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dan emery
Joined: 11 Jan 2004
Posts: 6884
Location: Maine

7/11/13 9:47 AM

different approach

Why not ask a dealer what the spec/practice is for your car? If they want you to get new tires, and the adjuster accepts it, why not? If they tell you not to worry about it, don't.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/11/13 9:55 AM

Additional note: When shopping for the new tires we where considering, we looked into road hazard coverage on the new set. Asking if the situation repeated itself would the road hazard cover a new set. Answer was no, FWIW. They would have only covered the one damaged tire and we would have had to buy the other three with an adjusted price for miles on the damaged one only.

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/11/13 12:46 PM


quote:
Why not ask a dealer what the spec/practice is for your car? If they want you to get new tires, and the adjuster accepts it, why not? If they tell you not to worry about it, don't.


The dealer of course "recommends" 4 new ones. Though curiously enough, they didn't insist on I must. Hence my original question of whether there's much merit in replacing all of them in the first place.

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dan emery
Joined: 11 Jan 2004
Posts: 6884
Location: Maine

7/11/13 1:02 PM

Well then

I'd see if the dealer can cite a specific spec or standard, and either way take the recommendation to the adjuster. Unless you'd rather not have new tires.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/11/13 2:41 PM

My dealer mistrust is high these days. My first thought is they would rather have the repairs that the tire sale. Especially it is at the hear-say level on the recommendation.

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/11/13 3:05 PM


quote:
I'd see if the dealer can cite a specific spec or standard, and either way take the recommendation to the adjuster.

I will ask them for it. If they could come up with one, I would certainly show it to the adjuster. That, would be worth the shot.

I'm pretty sure the insurance adjuster won't fall for the "recommendation" alone without the spec though. Especially when the car is over 100k, I have more to worry just to get it repaired with OEM over "refrab" parts, rather than fishing for any "extras"...

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dan emery
Joined: 11 Jan 2004
Posts: 6884
Location: Maine

7/11/13 4:37 PM

Fight for OEM

No personal experience, and I no longer own a Saab, but I still check a Saab forum and alot of the discussion indicates that many non-OEM parts REALLY SUCK! Rebuilt parts may actually be better than many of the knockoffs. But I'd always try for OEM.

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/11/13 5:26 PM

I've not owned any high value cars in the past. And I do tend to keep my cars for a while instead of keep trading them in. So, I noticed at some point the insurance company would start to put on used/refrab/non-OEM parts!

This is the first time I have a car that has the highest mileage and year that requires insurance work. (I've owned cars longer/older but they didn't happen to require insurance work at their older age). Being a premium end brand, the car's current value at this point is still higher than many of the newer cars I've had to get work done! So naturally I worry a bit about at which point they're going to start to nickle and dime me.

Though to my advantage in this case, it's a relatively cheap work compare to any collision involving body work.

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ErikS
Joined: 19 May 2005
Posts: 8337
Location: Slowing boiling over in the steamy south, Global Warming is real

7/12/13 3:07 AM

So wha kinda car is it? Some may be more tolerant than others based on reputation.

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/12/13 9:46 AM

BMW-3

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sandiway
Joined: 15 Dec 2003
Posts: 4902
Location: back in Tucson

7/12/13 10:01 AM

April,

I used to have a BMW 3 series awd and have some relevant experience.

When I punctured on a road trip to visit Jimbo years back, and had to wait two days for a replacement new tire (I was in the boonies), it wasn't necessary to replace all of them. And the awd system didn't suffer.

I can't say the same for the rest of the BMW post-warranty period. Items crapped out on a regular basis...

Sandiway

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Jesus Saves
Joined: 16 Jun 2005
Posts: 1150
Location: South of Heaven

7/13/13 6:07 AM

That mattered years ago. Unless you current set of tires are quite worn you should be fine.

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