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AAA:Replace worn tires at 4/32nds inch tread depth

Posted By: tenderloin

AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 12:34 PM

AAA 4/32 Tire Replacement

RLANDO, Fla.ó Citing safety concerns related primarily to wet braking, AAA Inc. is recommending consumers replace their worn tires at 4/32nds inch tread depth.

Nationwide car owners' club AAA is basing its stance on the results of tests it conducted recently on new and worn tires, which showed significant increases in braking distances in wet conditions as tires wear.

"Tires are what keep a car connected to the road," John Nielsen, AAA's managing director of automotive engineering and repair, said.

"Even the most advanced safety systems rely on a tire's basic ability to maintain traction, and AAA's testing shows that wear has a significant impact on how quickly a vehicle can come to a stop in wet conditions to avoid a crash."

AAA conducted its testing in partnership with the Automobile Club of Southern California's Automotive Research Center. Those tests compared the wet braking performance of new all-season tires and those worn to a tread depth of 4/32nds inch.

According to the tests, tires worn to a tread depth of 4/32nds inch exhibit the following, compared with a new tire:

ē An average increased stopping distance at highway speeds of 87 feet for a passenger car and 86 feet for a light truck; and

ē A 33-percent reduction in handling ability, for a passenger car and 28 percent for the light truck on average.

AAA's testing involved a Toyota Camry and Ford F-150.

Tires tested on the Camry were: Nexen Classe Premiere CP671; Goodyear Eagle Sport; Fuzion Touring; Pirelli Cinturato All-Season Plus; Kumho Ecsta 4X II; and Michelin Premier A/S.

Tires tested on the Ford F-150 were: Firestone Destination LE II; Bridgestone Dueler H/L Alenza Plus (113T); Cooper Evolution H/T (115T); Michelin Defender LTX M/S (115T); Hankook Dyanpro RH12 (113T); and Goodyear Wrangler Fortitude HT (115T).

The complete results are available on AAA's website.

"AAA's testing demonstrates the impact that tire tread has on safety," Megan McKernan, manager of the Automobile Club of Southern California's Automotive Research Center, said.

"If tested side-by-side at 60 mph, vehicles with worn tires would still be traveling at an alarming 40 mph when reaching the same distance it takes for vehicles with new tires to make a complete stop."

AAA said its research found that tire performance does vary by brand, but price is not necessarily an indicator of quality. Worn tire performance deteriorated significantly for all tires tested, including those at a higher price point.

AAA advises shoppers to research options carefully before selecting a replacement tire for their vehicle, and never choose one based on price alone.

"With newer cars going longer intervals between routine maintenance at automotive service facilities, drivers may not become alerted to the fact their tires are too worn until it's too late," Mr. Nielsen said.

AAA's comprehensive evaluation of tire tread laws and regulations across U.S. states found state requirements range from inadequate to non-existent.

Forty-two states consider 2/32nds inch the minimum legal tread depth. California and Idaho have set the minimum at 1/32nd, while Arkansas, Montana, New Mexico, North Dakota, South Carolina and West Virginia have no legal mininum standards.

The AAA's recommendation is in contrast with Michelin North America Inc.'s contention that removing tires prematurely from service costs consumers billions of dollars and increases the amount of scrap tires to be dealt with.
Posted By: tig1

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 12:35 PM

Where I come from we call it 1/8.
Posted By: supton

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 12:56 PM

When I get to 4/32's I start thinking about replacing. Nothing new here, I thought AAA (and others?) had been pressing for this for years?

Between 2/32's and 4/32's I adjust my driving, knowing that traction might be lowered in rain. Before anyone yells at me that I should remove "unsafe" tires--a similar argument could be said to buy the car with the shortest stopping distance, and anything longer than that is putting everyone at risk. And that driving a twenty year old car is automatically unsafe simply because it's been surpassed.
Posted By: Donald

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:00 PM

I think at 4/32" one should be making their plan to get the tires replaced in the near term. And of course if a Subaru symmetric AWD then all 4 tires need replacement.
Posted By: Astro14

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:05 PM

I replace them at 4/32 most of the time, as that's the depth at which wet performance begins to significantly degrade.

Legal minimum and safe aren't the same thing, most of the time...
Posted By: CT8

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:06 PM

Originally Posted By: tig1
Where I come from we call it 1/8.
4/32 sounds more high tech.
Posted By: Shannow

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:14 PM

Sad thing is that the tread wear bars alter (not by much, but they do) the wet weather performance of tyres.

But by defining the legal minimum, they at least give something to quantify compliance to an arbitrary definition of safety...a "go-nogo" principal that can be applied at the side of the road.

(used to be "match heads" down here..if a match head could be hidden in the tread over 75% of the tread area, they were legal).

at 275 thousandths, the Deuller H/Ts on my Colorado failed my wet weather standards...and I replaced them
Posted By: Char Baby

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:18 PM

This is why I always say that half tread is actually 6/32nds.
If most passenger tires(generally) start out at 10/32nds, and are only good(by law) down to 2/32nds, then 6/32nd is our(OUR) real 1/2 tread mark. Not according to the tire industry or safety organizations but, to me. Think about it!

Others have disagreed & will continue to disagree with me.

I too start thinking about buying new tires somewhere between 5-6/32nds and depending on the season, I'll get rid of them by 3-4/32nds.
Posted By: Sayjac

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:18 PM

Quote:
Where I come from we call it 1/8.

If one looks a standard tire tread depth gauge, the gradations are by 32nds.

So 4/32nds basically saying the quarter test now more appropriate than the penny test.

Corresponds to display sign information now found in DT stores.

https://www.discounttire.com/learn/tire-safety

Posted By: sasilverbullet

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:51 PM

Nothing new, Porsche has been preaching this for 30 years. They do their own tire studies/research.
Posted By: ARCOgraphite

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 01:55 PM

Usually when mine are at 1/8 in the center, they are showing the belts and cord on the edge smile
Posted By: Ducked

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 02:12 PM

So if I want to maximise my bald tyre wet weather performance, I should drive a light truck, rather than a car.

Good news in the US, I'd have thought.
Posted By: ctrcbob

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 02:36 PM

I go by the wear bars. 2/32nds. Been that way for years. With the price of quality tires today, I'll continue at 2/32.
Posted By: Richie

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 03:10 PM

I do the same.

Originally Posted By: Astro14
I replace them at 4/32 most of the time, as that's the depth at which wet performance begins to significantly degrade.

Legal minimum and safe aren't the same thing, most of the time...
Posted By: 69GTX

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 04:02 PM

With AAA's concern over tread depth, I'm surprised they didn't also mention age and/or UV cracking. Most people can see a tire wearing. Most don't really key on cracking or age until the tire is really worn. Recommendations on retiring a tire based on age are all over the map too. Then you have the issue of good tread, no cracking, yet the tire is 6-10 yrs old...or older. What then?
Posted By: Wolf359

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 04:10 PM

I start thinking about it when they hit 5/32's and start to get rid of them at either 3 or 4/32's. If they're less than 5/32's for the winter, I get rid of them then. 5/32's is about as low as you can go for good snow performance, 4/32's is for rain.
Posted By: mclasser

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 04:27 PM

This means more business for the tire industry, but I can see the safety aspect as well. In snow and rain country, 4/32" is a good time to replace.
Posted By: Rmay635703

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 04:34 PM

Originally Posted By: ctrcbob
I go by the wear bars. 2/32nds. Been that way for years. With the price of quality tires today, I'll continue at 2/32.


Exactly, typically my sidewalls blow well before that anyway
Posted By: PimTac

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 05:07 PM

Nobody keeps pennies in their pockets anymore so this is the standard.

I agree with Tig. 1/8 should be used. I was taught to reduce fractions when possible.
Posted By: jjjxlr8

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 05:43 PM

Originally Posted By: Rmay635703
Originally Posted By: ctrcbob
....


....typically my sidewalls blow well before that anyway


Really??? That shouldn't be the case unless they are run underinflated.
Posted By: jjjxlr8

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 05:44 PM

Originally Posted By: PimTac
Nobody keeps pennies in their pockets anymore so this is the standard.

I agree with Tig. 1/8 should be used. I was taught to reduce fractions when possible.


Traditionally, tire tread depths are measured in 32nd's for people who can't convert fractions in their heads. It's easier for consumers to compare if the denominator is common. smile
Posted By: Voleak

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 06:01 PM

Where I always buy tires, Discount Tire, they also recommend replacing tires at 4/32nds. And I fully agree with that, but, some (or all?) tire manufacturers require that consumers use their tires until 2/32nds in order to file a treadwear warranty. Tires must be fully worn to 2/32nds, and evenly worn to submit a claim -sound familiar?

This conflicts with the safety of consumers and our nations roads. I never get a credit for my used tires because I put my safety and others, above a small allowance towards new tires.

I am sure there are a lot of people that want to get their moneys worth, and get an allowance towards their next set of tires. I can't blame them, as it's required by tire manufacturers to drive on dangerously low tread depths to get a piece of that almighty marketing scheme treadwear warranty. But, this puts them and others at risk because they cannot brake, steer, or control their vehicles as effectively.

I replace at around 5/32 - 4/32.
Posted By: Rmay635703

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 06:09 PM

Originally Posted By: jjjxlr8
Originally Posted By: Rmay635703
Originally Posted By: ctrcbob
....


....typically my sidewalls blow well before that anyway


Really??? That shouldn't be the case unless they are run underinflated.


I keep my tires around 40 psi, tire manufacturers donít cover sidewalls because that is how most tires fail.
Posted By: kschachn

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 06:12 PM

Originally Posted By: Rmay635703
Exactly, typically my sidewalls blow well before that anyway

I find that an amazing statement. Never in my 40+ years of driving have I personally ever had a tire fail other than due to a puncture or other damage, much less have a sidewall "blow".
Posted By: Leo99

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 06:33 PM

Originally Posted By: kschachn
Originally Posted By: Rmay635703
Exactly, typically my sidewalls blow well before that anyway

I find that an amazing statement. Never in my 40+ years of driving have I personally ever had a tire fail other than due to a puncture or other damage, much less have a sidewall "blow".


Yup, never had a sidewall blow.
Posted By: jjjxlr8

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 07:28 PM

Originally Posted By: Rmay635703
Originally Posted By: jjjxlr8
Originally Posted By: Rmay635703
Originally Posted By: ctrcbob
....


....typically my sidewalls blow well before that anyway


Really??? That shouldn't be the case unless they are run underinflated.


I keep my tires around 40 psi, tire manufacturers donít cover sidewalls because that is how most tires fail.


Yeah, that's not typical at all. Are you talking about getting a sidewall puncture or damage to the sidewall? That's a different situation entirely.
Posted By: jjjxlr8

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 07:29 PM

Originally Posted By: Voleak
Where I always buy tires, Discount Tire, they also recommend replacing tires at 4/32nds. And I fully agree with that, but, some (or all?) tire manufacturers require that consumers use their tires until 2/32nds in order to file a treadwear warranty. Tires must be fully worn to 2/32nds, and evenly worn to submit a claim -sound familiar?

This conflicts with the safety of consumers and our nations roads. I never get a credit for my used tires because I put my safety and others, above a small allowance towards new tires.

I am sure there are a lot of people that want to get their moneys worth, and get an allowance towards their next set of tires. I can't blame them, as it's required by tire manufacturers to drive on dangerously low tread depths to get a piece of that almighty marketing scheme treadwear warranty. But, this puts them and others at risk because they cannot brake, steer, or control their vehicles as effectively.

I replace at around 5/32 - 4/32.


So you probably wouldn't buy a Michelin Premier AS as they only have 8.5/32nds when new. You would be replacing them with over half of the tread life remaining!
Posted By: Rmay635703

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 07:40 PM

Originally Posted By: kschachn
Originally Posted By: Rmay635703
Exactly, typically my sidewalls blow well before that anyway

I find that an amazing statement. Never in my 40+ years of driving have I personally ever had a tire fail other than due to a puncture or other damage, much less have a sidewall "blow".


The sidewall blows or starts to leak, Iíve only had two sets of tires die due to wear, both on cars,
On my suburbans, motorhome and trucks my tires always were replaced after one had some sort of sidewall failure.

I donít think Iíve ever replaced a tire on a truck or motorhome due to wear.

Motorhome was the worst because the sidewalls would crack pretty bad after 2 or 3 years
Posted By: supton

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 08:04 PM

Originally Posted By: Voleak
Where I always buy tires, Discount Tire, they also recommend replacing tires at 4/32nds. And I fully agree with that, but, some (or all?) tire manufacturers require that consumers use their tires until 2/32nds in order to file a treadwear warranty. Tires must be fully worn to 2/32nds, and evenly worn to submit a claim -sound familiar?


Yep, which is why I don't bother looking for the highest mile rated tire. I want to get them off before 2/32's. So the warranty is useless to me. That and in my area nobody gets more than 40k out of a set it seems.
Posted By: Voleak

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/08/18 08:06 PM

So you probably wouldn't buy a Michelin Premier AS as they only have 8.5/32nds when new. You would be replacing them with over half of the tread life remaining![/quote]

That is correct, I will not use Premier A/S. I will continue to use Nokian, Cooper, and Continental tires. The models I like by them run 11 - 12/32nds.
Posted By: Nick1994

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 12:41 AM

My tires are probably around 6/32Ē on the Sonata. Iím considering running them down to 2/32Ē at least, since it doesnít rain here hardly ever. But if rain is in the forecast when my tires are low on tread I can always just either drive the Camry or the Jeep.

Not sure I can handle it though, these Kumho tires are driving me insane with how loud they are.
Posted By: asiancivicmaniac

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 02:47 AM

After hydroplaning on tires with about 3/32nds on them down I75 during a torrential downpour, I replace tires around 4/32nds if not slightly more.

I just had new tires put on the Fiesta yesterday and the difference in how they cut through standing water compared to the old ones at 4/32nds that came off is huge.
Posted By: Ducked

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 03:39 AM

These tests have, until fairly recently, been all over the place, with some reporting no significant difference at these tread depths. Recently this seems to be the concensus, perhaps because tyres are now wider.

OTOH, dry tyre performance is said to improve with lower tread depth. Probably a smaller effect, but since I drive in the dry MUCH more often than I drive in the wet (and almost completely reliably dry in season), statistically I might be no worse off on low-tread tyres.
Posted By: Kibitoshin

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 04:37 AM

Originally Posted By: jjjxlr8
So you probably wouldn't buy a Michelin Premier AS as they only have 8.5/32nds when new. You would be replacing them with over half of the tread life remaining!


Considering their "safe when worn" claim means when the tire is worn to 4/32".
Posted By: CapriRacer

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 11:58 AM

Originally Posted By: Rmay635703
Originally Posted By: ctrcbob
I go by the wear bars. 2/32nds. Been that way for years. With the price of quality tires today, I'll continue at 2/32.


Exactly, typically my sidewalls blow well before that anyway


My experience is quite different, but I suspect we have a terminology problem. If the tires are "failing the inspection procedure", rather than "had a structural failure", then it makes sense. Sidewall cracking is a good indicator of the state of the rubber and frequently is the criteria for removal.
Posted By: Ducked

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/09/18 10:04 PM

Originally Posted By: CapriRacer
Originally Posted By: Rmay635703
Originally Posted By: ctrcbob
I go by the wear bars. 2/32nds. Been that way for years. With the price of quality tires today, I'll continue at 2/32.


Exactly, typically my sidewalls blow well before that anyway


My experience is quite different, but I suspect we have a terminology problem. If the tires are "failing the inspection procedure", rather than "had a structural failure", then it makes sense. Sidewall cracking is a good indicator of the state of the rubber and frequently is the criteria for removal.


Don't think you can fail a UK MOT inspection on sidewall cracking unless they can see tyre fabric, assuming they follow the rules.
Posted By: turboseize

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/10/18 10:24 PM

Autobild testet some all-seasons on new thread, 4mm and 2mm. Turns out four of the six tyres tested were becoming dangerous at 4mm, but Goodyear and Michelin were ok even at 2mmm...

http://www.autobild.de/artikel/ganzjahresreifen-reifenprofiltiefen-im-test-878052.html
Posted By: IndyIan

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/13/18 02:19 AM

Originally Posted By: Ducked
These tests have, until fairly recently, been all over the place, with some reporting no significant difference at these tread depths. Recently this seems to be the concensus, perhaps because tyres are now wider.

OTOH, dry tyre performance is said to improve with lower tread depth. Probably a smaller effect, but since I drive in the dry MUCH more often than I drive in the wet (and almost completely reliably dry in season), statistically I might be no worse off on low-tread tyres.

The sport comp2's on the Focus are down to the 3-4/32, and now they feel very nice. No squirmy tall tread left, so they turn right away. The car seems to track straighter and feels more connected to the road, also no squirm on acceleration either. I don't worry about grip on wet pavement, but I am a bit more careful with aquaplaning, but they aren't super wide.
They are AA wet traction rated so were way ahead of most tires to start with, so if they only work as good as most new 3 season tires, I'm OK with it.
Posted By: jakewells

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/13/18 04:19 AM

I run my tires till the tread is so thin i can see the air through the tire.
Posted By: LotI

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 04:40 AM

AAA


The full report for those who like facts. One of the objectives of the study was to find if value tires performed differently than expensive tires.
Posted By: Shannow

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 10:54 AM

Originally Posted By: LotI
AAA


The full report for those who like facts. One of the objectives of the study was to find if value tires performed differently than expensive tires.


That's an impressive set of data.

Thanks
Posted By: krzyss

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 12:47 PM

Michelin Premier A/S beats all others in performance numbers when new and when worn.
Goodyear Eagle was designed for 'Uneven Concrete' based on its noise data.

Michelin equipped Camry stops in 192.25ft when new vs 229ft worse contender.
Michelin equipped Camry stops in 247.01ft when worn vs 326.7ft worse contender.

New cheap better than old expensive.

Krzys
Posted By: Snagglefoot

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 12:54 PM

I bought a cheap thread wear indicator. Takes the guesswork out of it.
Posted By: nap

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 01:32 PM

Originally Posted By: krzyss
Michelin Premier A/S beats all others in performance numbers when new and when worn.


I'm curious about your choice from a comfort perspective. Which is what the "Grand Touring" tire category is supposed to address.
Posted By: CapriRacer

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 01:41 PM

Originally Posted By: LotI
AAA


The full report for those who like facts. One of the objectives of the study was to find if value tires performed differently than expensive tires.


What jumped out at me was the differences between brands (which was confounded by the exact model.) I know there are ways to sort out the effect model (brand) had, but while I am sophisticated enough to know they didn't use the technique, I am not sophisticated enough to do it myself.

Personally, I wonder how rigged the test results were. I note that the test was conducted at a Michelin test facility and I would guess that much of the equipment used was Michelin in-house equipment. Home field advantage?

On the other hand, the published results are saying that cheap tires are just fine - which I would think would NOT be what Michelin would want.

I also note that the test results were directionally towards more expensive tires being better, it just wasn't at a 95% confidence interval - and what I know about traction testing is that these things are highly variable, so it's not a surprise they didn't get 95%.
Posted By: krzyss

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 02:14 PM

It is quite possible that Michelin tires tested on Michelin turf will have some edge.
From performance and noise numbers it seemed that Goodyears did not belong to high end tires except the concrete surface noise levels that was the lowest.
Maybe they were developed on different surfaces.

I think objective was to show that worn tires suck at 4/32 in wet regardless of price point. In my opinion they showed that best wet tires outbrake the worst by 30+ ft and that is a lot, at least for me.

Krzys
Posted By: nap

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 02:21 PM

Originally Posted By: CapriRacer


Personally, I wonder how rigged the test results were.


The only unusual thing there that I noticed is that they shaved all tires to 4/32 regardless of how much thread they start with.

The Premier starts with 8/32 and is designed specifically to keeps sipes until late stages of wear.

The others start more generously at 10/32 or more and the sipes are erased earlier than 4/32.

Maybe they should have checked against a Continental with DWS markings and shave it borderline to making the W (wet) marking disappear. As that is the clear indication from the manufacturer on what the thread depth should be in order to guarantee the wet performance.

Or maybe they should have shaved 4/32 FROM all tires (instead of shaving TO 4/32).

You can easily notice the differences from the pics.
Posted By: supton

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 06:29 PM

Flipped through the report. At the risk of being rude... even Michelin didn't do that well. Once worn, even the worst cheapo tire did better (when new).

Good testing, but IMO it opened up a new question, at for me: what does the curve look like, as one goes from full depth to mid depth to 4/32? Is 6/32 really close to new--or is it half between?
Posted By: SirTanon

Re: AAA:Replace worn tires at 4/32nds inch tread depth - 06/18/18 07:09 PM

This video is an interesting analysis of the AAA study.. If you haven't watched this guy's channel before, it's definitely worth checking out.

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