One tyre worn, replace them all ?

[Shannow]

Mate at work took his Commondore SV-6 (Sort of a Pontiac G-8 in G-6 version) in for a service, and the right rear tyre (previously associated with a nasty clunking sound at highway speeds) was deemed unserviceable.

"However, Holden require that all four tyres are replaced as a set".

They are only $250-$300 each.

Why do they require that ?

An axle's worth maybe, but if the car's destroyed one tyre on the axle, it's working with a heavily worn tyre and a moderately worn tyre. Replace just one, and it's still new versus moderately worn.

Even front to rear rotation ain't much different.

 

[moribundman]

Originally Posted By: Shannow
"However, Holden require that all four tyres are replaced as a set".


They forgot mandating a new spare tire!

 

[Shannow]

Hmm, will set him onto that tomorrow

 

[JHZR2]

question is how much tread is left on the other tires??? Is it less than 50%?

I dislike mismatched tires, but wasting perfectly good tires is a big deal and cost too. Id say to replace by the axle at least, unless the other three are more or less brand new (doubtful).

More importantly, he should get to the bottom of why one of the four was unserviceable and needed replacement...

 

[Papa Bear]

How can Holden dictate how many tires you have to buy ???

 

[Bill in Utah]

On a AWD vehicle you have to change ALL of them if any tire is more than a 1/4 of a inch circumference.

When the Outback was hit @ 8,000 miles, a replacement tire (same brand and model/size) was almost 2" larger and the car had major issues. I had to trade in all tires and buy 4 new.

Also, there is a sign in most tire shops stating that tires have to be replaced in pairs except 4x4/AWD which is all 4.

Good times.

Bill

 

[Kestas]

There may be some merit to these requirements. Modern cars now have a wheel speed sensor for each corner. Antilock brakes, traction control, and electronic vehicle stability functions depend on each wheel to have the same diameter, or else these functions may be falsely activated. A new tire will not be the same diameter as a used one. This is where Bill's reference to 1/4-inch (circumference or diameter?) difference between tires comes to play.

These electronic functions and upcoming tire pressure monitors will make tire management expensive and a real challenge for the future.

 

[eljefino]

I would try long and hard for a used tyre with similar treadwear. If they're OE you should have a pretty easy time getting the exact same model (important for diameter measurement) as many get sick of them before they're done.

 

[alreadygone]

Originally Posted By: eljefino
I would try long and hard for a used tyre with similar treadwear. If they're OE you should have a pretty easy time getting the exact same model (important for diameter measurement) as many get sick of them before they're done.



Or, have one wear out early and go ahead and buy the set, then tire shop has 3 perectly good used ones laying about needing a new home.

I'm strongly with El jeffie here, do a little checking around and get one used to finish out remaing three. THEN buy set of new.

Bob

 

[exranger06]

Originally Posted By: Kestas
There may be some merit to these requirements. Modern cars now have a wheel speed sensor for each corner. Antilock brakes, traction control, and electronic vehicle stability functions depend on each wheel to have the same diameter, or else these functions may be falsely activated. A new tire will not be the same diameter as a used one. This is where Bill's reference to 1/4-inch (circumference or diameter?) difference between tires comes to play.

These electronic functions and upcoming tire pressure monitors will make tire management expensive and a real challenge for the future.

+1. It will also burn up a limited slip differential, if so equipped.

 

[Bobert]

Originally Posted By: Bill in Utah
On a AWD vehicle you have to change ALL of them if any tire is more than a 1/4 of a inch circumference.

When the Outback was hit @ 8,000 miles, a replacement tire (same brand and model/size) was almost 2" larger and the car had major issues. I had to trade in all tires and buy 4 new.

Also, there is a sign in most tire shops stating that tires have to be replaced in pairs except 4x4/AWD which is all 4.

There is a good article here about changing tires on AWD vehicles.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18

The "set in stone" notion that one must swap all four tires out on AWD vehicles is overly simplistic and obviously make $$ for a tire shop. Use the owners manual as your guide.

They give a few examples for different manufactures at the end of the article. Obviously with different makes and/or models the recommendation might change.

--Audi: As published in their vehicle owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining tread depth.

--Porsche: Cayenne within 30% of the other tire on the same axle's remaining treadwear.

--Subaru: Within 1/4-inch of tire circumference or about 2/32-inch of each other in remaining tread depth.

There is also the option of shaving a tire to the correct depth if you only want to replace one tire. Better than shelling out the big bucks for 4 new ones.

 

[Volvohead]

To the OP: Unless the rest are near the end, buy one new tire and have it SHAVED to matched depth. That's how AWD owners deal with it.

 

[moribundman]

Originally Posted By: Bobert
--Audi: As published in their vehicle owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining tread depth.


For my '96 A4 quattro the manual states that the circumference of all tires must not exceed 3% between all tires. For the past 12 years I have not run into any issues. I have never measured actual circumference, but I do rotate my tires (front to rear and vice versa) when I eyeball more than a 2 mm difference in tread depth between front and rear.

 

[rpn453]

Originally Posted By: Shannow
Why do they require that?


To relieve themselves of liability and to help their dealers make money.

I wouldn't replace a single tire unless the others are still in like-new condition, but I often replace tires in pairs.

 

[mstrjon32]

I'm running one new Eagle LS2 and three more worn LS2's (maybe 4/32 or 5/32'nds left) on my 2006 Monte Carlo. The new tire is on the rear axle (front wheel drive). Other than making my alignment 'feel weird', for some reason I still don't fully understand, I've had no problems with this arrangement. When the other 3 start to show wear bars or whatever, all 4 will get replaced and I'll keep the newer one as a full size spare. I put the tire on the car myself so there was no annoying shop to deal with or try to sell me additional tires.

On my Cherokee I've got an unmatched tire as well, came that way from the previous owner. When I bought it, it was on the rear axle, but I rotated it up to the front just for good measure. Since it's only a part-time 4WD system that can't be used on hard surfaces anyway, it's just fine this way.

 

[Bill in Utah]

Originally Posted By: Volvohead
To the OP: Unless the rest are near the end, buy one new tire and have it SHAVED to matched depth. That's how AWD owners deal with it.
No one will shave a tire here due to our wonderful law system. I tried every place before I spent the $$$ for all new tires on a new car with 8k on it.