Shaved tires last longer. Myth, or true?

[JCH13]

And that's how you give a civilized response. Thanks, and we can just agree to disagree.

All I'll mention is that, well, interstates are usually straight. At least the ones in my city are; I know on some terrain they can wind a little more. You're not typically under the forces that would make the car spin- the intertia is pointed forward. Therefore, I would still have to say that I would prefer to feel the back end 'float' a little rather than temporarily lose the ability to make steering corrections.

If the road is straight then you do not need to steer and thus understeer is acceptable.

Your assumption about the car NOT being under forces that will cause it spin sideways is not valid. If there is any different in braking force between the two front tires there will be a 'spinning' torque applied to the vehicle. With possibly varying pools of water, different amounts of moisture on each rotor, the possibility of one caliper working differently than the other, and one tire having slightly better grip than the other, the chances of un-even braking forces are a near certainty.

Normally, I would accept information from a very old, very large tire manufacturer as true; but I simply think that in this particular case, it is based on some engineer's 'calculations' regarding handling performance rather than real world problems. There's just not anything that would make ME feel more comfortable with bad front tires than bad rear tires. Perhaps the latter does have more potential to cause a catastrophic accident for 'most' drivers (meaning...bad drivers). I'm just surprised that so many people who assumably know how to handle themselves pretty well are so worried about completely losing control because of oversteer.

Automotive engineers, specifically chassis dynamics guys, really know their shit. They have complete spectrums of test data based on real world testing. They don't just pencil-whip problems at a desk, they test, they drive, they refine, then they test some more. It's something many people never think about and never see, but I have seen first-hand in college and in my professional career.

If you noticed in that article the Michelin guys say that every driver spins during this test and they KNOW they're in a shitty situation and they are PROFESSIONALS who drive cars hard every day. You're damn right I'm worried about spinning from hydroplaning, and more importantly I don't want my significant other to spin if she hydroplanes.

A proposed test: take two pairs of those plastic crates that companies use to ship soda to convenience stores. Put one pair under the rear wheels of a FWD. Put the other under the front wheels of a RWD. Observe which one is easier to control. edit: this is best demonstrated in the rain, since your 'sliding' axle won't have so much friction against the ground.

Just go along on a slippery road and rip the e-brake to lock up your rear wheels.* Keep it on until you come to a complete stop from ~50mph. Take a video and show us how it was easy to keep the vehicle in a straight line. This is the sort of situation I think is dangerous.

*Don't actually do this, you'll probably crash.

 

[phucheneh]

It's almost comical that I disagree with pretty much every point you make. I'm not trying to be a dick about it, you'd just think we'd have some amount of overlapping agreement, depending on the situation. Your first paragraph is what really puzzles me.

1) In that situation, it's not understeer. It's 'no steer at all.' Even on an apparent straight, you need the ability to make minute corrections.
2) If the car is under forces that could make it spin...again, I would want my steering wheel to function so that I can counter it.
3) Where did braking come in? You don't need to be braking if you're hydroplaning... you take your foot off gas/brake, hold steering wheel straight and/or provide correction as is needed. If you panic and stab the brakes, you'll turn a brief loss of traction through a puddle into 'locked' brakes on the wet pavement beyond.

Part of this debate is that everyone wants to think of their own situation and use their own experiences. I'm trying to seperate all the various factors and put things on an even playing field.

The biggest point of argument seems to be that at speed, in a fairly significant, flat turn, people are worried about the back end coming around. Again, while this is significant in racing (although I doubt most pro drivers would say 'I'd rather be sliding into the wall with no control whatsoever'), it is not on the street. If you are frequently fighting disastrous oversteer in your daily driver, perhaps you should slow down.

Again, we're just not going to agree. I put in the last bit (and started talking about hydroplaning in general) as a last ditch effort to try and sway someone to at least admit that, 'well, under THOSE circumstances...'

So we should just call it quits here. I'm sure I've pulled the ebrake at speed when I was a kid. I never lost control, and that's while intentionally going sideways just to, well, be a stupid kid. In a straight line? Yes, I could stop fine, because I have steering to compensate for the back end moving around. It's not exactly like trying to recover mid-donut.

I'm not endorsing (real, RWD) drifting; I think it's a dumb sport. But it's notable to mention that by some of this logic, what those guys do is complete magic.

 

[phucheneh]

One more thing to note...God this thread is like an AIDS-free five dollar whore with all her teeth (you might keep coming back, but you'd probably not be proud of it).

...that's not the thing. It's that:

One part of our disagreement, especially given extreme juxtaposition (i.e. two bald tires and two great tires), is that neither side (I'm including myself) wants to look at big picture regarding what effects would be noticed on the good tires and the car as a whole. You're just thinking you'd want to avoid dangerous oversteer, but ignoring how utterly unsafe bald front tires are in the rain. I'm thinking about how much I ALWAYS want to have the ability to have some kind of steering input, but am not really considering the forces the car would be under if the back end gets irreparably chucked out from under you.

Fair to say?

 

[JCH13]

One more thing to note...God this thread is like an AIDS-free five dollar whore with all her teeth (you might keep coming back, but you'd probably not be proud of it).

...that's not the thing. It's that:

One part of our disagreement, especially given extreme juxtaposition (i.e. two bald tires and two great tires), is that neither side (I'm including myself) wants to look at big picture regarding what effects would be noticed on the good tires and the car as a whole. You're just thinking you'd want to avoid dangerous oversteer, but ignoring how utterly unsafe bald front tires are in the rain. I'm thinking about how much I ALWAYS want to have the ability to have some kind of steering input, but am not really considering the forces the car would be under if the back end gets irreparably chucked out from under you.

Fair to say?

You have greatly exaggerated my opinion by saying "bald tires". I would never run bald tires in the rain. I'm also not ignoring the considerable draw-backs of not having four good tires, that configuration was not part of the original discussion of 'where to install two new tires.'

The real difference in this discussion is that one opinion is endorsed by virtually every industry expert and has been confirmed by testing while the other has not.

 

[phucheneh]

You have greatly exaggerated my opinion significantly by saying "bald tires". I would never run bald tires in the rain. I'm also not ignoring the considerable draw-backs of not having four good tires, that configuration was not part of the original discussion of 'where to install two new tires.'

The real difference in this discussion is that one opinion is endorsed by virtually every industry expert and has been confirmed by testing while the other is not.

That opinion assumes your goal is optimal handling characteristics on a car with two new tires and two slightly worn tires.

I don't think I ever said that, hence my using hypothetical 'worst case scenarios' to demonstrate my point. I was talking about the all-too-common situation of two new tires and two <50% tires. I was also initially talking about even tire wear (more tread on front...which becomes less tread on front...then you rotate).

The manufacturer recommendations concerning installing two tires, if they even say it's acceptable at all, are going to assume the remaining two tires are in very good condition. To do otherwise would be to open themselves up to liability.

And if all the tires are good, who gives a shit what position they're in? Hence I would default to positioning them for optimal tire life. I share my opinion with the majority of the automotive service industry in my large city. I guess we're just in some kind of weird bubble. Also, people tend to, you know, not have money. So if they are in need of two tires but can't afford it, I recommend what keeps them safer- best tires on front.

 

[Howard]

And that's how you give a civilized response. Thanks, and we can just agree to disagree.

All I'll mention is that, well, interstates are usually straight. At least the ones in my city are; I know on some terrain they can wind a little more. You're not typically under the forces that would make the car spin- the intertia is pointed forward. Therefore, I would still have to say that I would prefer to feel the back end 'float' a little rather than temporarily lose the ability to make steering corrections.

Normally, I would accept information from a very old, very large tire manufacturer as true; but I simply think that in this particular case, it is based on some engineer's 'calculations' regarding handling performance rather than real world problems. There's just not anything that would make ME feel more comfortable with bad front tires than bad rear tires. Perhaps the latter does have more potential to cause a catastrophic accident for 'most' drivers (meaning...bad drivers). I'm just surprised that so many people who assumably know how to handle themselves pretty well are so worried about completely losing control because of oversteer.

A proposed test: take two pairs of those plastic crates that companies use to ship soda to convenience stores. Put one pair under the rear wheels of a FWD. Put the other under the front wheels of a RWD. Observe which one is easier to control. edit: this is best demonstrated in the rain, since your 'sliding' axle won't have so much friction against the ground.

Did you happen to read this part of the article?

It didn't take long for this hands-on experience to confirm that the "proving grounds" name for the facility was correct. The ability to sense and control predictable understeer with the new tires on the rear and the helplessness in trying to control the surprising oversteer with the new tires on the front was emphatically proven.

And even though our drivers had the advantage of knowing we were going to be challenged to maintain car control, spinouts became common during our laps in the car with the new tires on the front and the worn tires on the rear. Michelin advises us that almost every driver spins out at least once when participating in this demonstration!

 

[MagickMan]

He is not. So let it go. If you want to have your own silly opinion, that's fine, but quit spreading misinformation to the general public.

Aren't you guys supposed to be enthusiasts? Rather than grumpy old men stuck in the sixties? Holy crap, I bet most of you do actually believe that setting a stored battery on a piece of wood keeps it charged.

We're grumpy? BUHAHAHA!! You've been in here blasting away, like Rambo with a bad case of hemorrhoids, being short-tempered, rude, and angsty with everyone. I'll let it go when I feel like it, and you can bite me. Pretentious snot.

 

[railer]

..........babbling deleted......QUOTE]


The things that you post are ill-informed at best, and simply dangerous at worst. You should really not be posting here at all, or at a minimum, only posting things that you fully understand. I'm not sure what those things might be at this point, but tire traction dynamics are definately not one of them. Thanks.

 

[phucheneh]

..........babbling deleted......

The things that you post are ill-informed at best, and simply dangerous at worst. You should really not be posting here at all, or at a minimum, only posting things that you fully understand. I'm not sure what those things might be at this point, but tire traction dynamics are definately not one of them. Thanks.

This is where I'm supposed to tell you do to something bad to yourself.

But I won't. Go be a happy happy sheep. I'm sorry that your grasp of the English language is so tenuous that my posts come off as 'babbling.' Read a book.

Howard- Yes, I read the article. Now actually read my posts.

Their test- drive around a wet corner with too much speed and see which tire configuration you find better for intentionally losing control of the vehicle.

Do you see the fundamental flaw? I do. Namely, that 'test' is absolutely retarded. Again, this is why engineers can suck it- go draw CAD or do some math. Leave the real world testing to people who don't think in a bubble. They're so focused on gathering data that they can't be bothered to think about what everyday driving actually consists of. Gee, so glad you got such a clear result from your empirically worthless test.

See earlier post that you must've missed.

The biggest point of argument seems to be that at speed, in a fairly significant, flat turn, people are worried about the back end coming around. Again, while this is significant in racing (although I doubt most pro drivers would say 'I'd rather be sliding into the wall with no control whatsoever'), it is not on the street. If you are frequently fighting disastrous oversteer in your daily driver, perhaps you should slow down.

Do you all not realize that most people actually don't attempt to drive through corners with their tires at the ragged edge of grip? The biggest concern is accident avoidance. Or just dealing with the unexpected, in general.

You know what happens when someone gets startled and must try to avoid having a wreck? Usually, they steer to the side of the obstacle (as in, steer slightly) and hit the brakes. You know what they don't do? Spin the steering wheel around and smash the accelerator. Surprise, guess which tire configuration benefits that first, non-retarded option? Yeah...

However, I do appreciate all the asshole comments from those who can't be bothered to read a well-thought out post, and instead prefer to just respond with kneejerk responses of 'NUH-UH THAT'S NOT WHAT I HEARD FROM TIRERACK!'

...and because they didn't read, they don't even know what they're responding to.

A++++++ QUALITY REPLIES, GUYS, WILL READ AGAIN!

And yes, being well-spoken and logical makes me a 'pretentious snot'...go eat some oat bran and have a poop, you'll feel better.

 

[jlee]

Are you fleabag's cousin?

 

[Howard]

Howard- Yes, I read the article. Now actually read my posts.

Their test- drive around a wet corner with too much speed and see which tire configuration you find better for intentionally losing control of the vehicle.

Whether they lost control accidentally, or induced loss of control intentionally, doesn't change the fact that the understeer that they experienced with better rear tires was EASIER TO CONTROL than the oversteer they got with better front tires.

 

[railer]

There is one single way to replace tires. There are not two sides, or two opinions. There is one method that is based on facts, data, and logic, and that method is endorsed by every tire manufacturer, ever car manufacturer, every legitimate tire shop, and every tire wholesaler/retailer.

The better tires go on the rear of the vehicle, independent of fwd, rwd, or awd.
This is done to minimize oversteer, which is inherently much more dangerous than understeer.
Anyone who doesn't do it that way doesn't have a "different opinion", they are simply wrong, and should not be posting on an automotive forum.

 

[Ferzerp]

There is one single way to replace tires

I'm going to be a pedant here since you're talking in absolutes (and have a retarded user picture). How do directional, staggered tires fit in to your black and white world?

 

[MixMasterTang]

This is where I'm supposed to tell you do to something bad to yourself.

But I won't. Go be a happy happy sheep. I'm sorry that your grasp of the English language is so tenuous that my posts come off as 'babbling.' Read a book.

Howard- Yes, I read the article. Now actually read my posts.

Their test- drive around a wet corner with too much speed and see which tire configuration you find better for intentionally losing control of the vehicle.

Do you see the fundamental flaw? I do. Namely, that 'test' is absolutely retarded. Again, this is why engineers can suck it- go draw CAD or do some math. Leave the real world testing to people who don't think in a bubble. They're so focused on gathering data that they can't be bothered to think about what everyday driving actually consists of. Gee, so glad you got such a clear result from your empirically worthless test.

See earlier post that you must've missed.



Do you all not realize that most people actually don't attempt to drive through corners with their tires at the ragged edge of grip? The biggest concern is accident avoidance. Or just dealing with the unexpected, in general.

You know what happens when someone gets startled and must try to avoid having a wreck? Usually, they steer to the side of the obstacle (as in, steer slightly) and hit the brakes. You know what they don't do? Spin the steering wheel around and smash the accelerator. Surprise, guess which tire configuration benefits that first, non-retarded option? Yeah...

However, I do appreciate all the asshole comments from those who can't be bothered to read a well-thought out post, and instead prefer to just respond with kneejerk responses of 'NUH-UH THAT'S NOT WHAT I HEARD FROM TIRERACK!'

...and because they didn't read, they don't even know what they're responding to.

A++++++ QUALITY REPLIES, GUYS, WILL READ AGAIN!

And yes, being well-spoken and logical makes me a 'pretentious snot'...go eat some oat bran and have a poop, you'll feel better.

I am not going to bother replying again, but there are scenarios that you are not accounting for.

Example: It's raining, your grand mother is going well under the speed limit but on a decent curve. An animal (or person) jumps out of the woods and she has to slam on the brakes to try and avoid hitting that person. In this scenario your grandma is going to be less likely to have her read end slide out on her *if* the best tires are on the rear.

 

[Meghan54]

...it's about correcting the absolute twaddle that you put in about 10% of your posts. Based on your posts here I wouldn't let you work on a lawn mower, let alone a car.

ZV

ZV, thank you for expressing so succinctly what most here were thinking to themselves. Hate it when these self-proclaimed "experts" show up here and want to impart their "knowledge" to us.

Hell, I even sent my brother links to several threads the aforementioned expert has posted in....gave him some big laughs. Not that my brother is any sort of expert, outside the fact he's been either working in a shop or running a shop for over 35 years, incl. having enough ASE certs. to patch both sleeves of his shirts, if he cared to do that.

C'est la vie.....thx, again, ZV.

 

[jagec]

It's amazing how reasonable-sounding an argument can be, while still being utterly and completely wrong. This thread is probably worse than the infamous "I inflate to sidewall" discussion.

I'd like to see this guy "steer better" when his rear end is racing the front and winning.

 

[phucheneh]

It's amazing how reasonable-sounding an argument can be, while still being utterly and completely wrong. This thread is probably worse than the infamous "I inflate to sidewall" discussion.

I'd like to see this guy "steer better" when his rear end is racing the front and winning.

The point is that the rear end would never be facing the front, as I've never felt the need to make massive, catastrophic over-corrections or go through a turn at twice the speed the vehicle can handle.

It's funny that I'm somehow the 'self-proclaimed expert' despite never proclaiming such...it seems more like that label has been assigned to me, and if I post something you disagree with, that label I had no intention of acquiring is suddenly my biggest failing.

I do not wear ASE patches on my shirt on hang anything on the wall. Believe it or not, I am not that type; I generally despise that type. I do not cite my professional work here unless I can give an example relevant to the topic, and I don't recall any of those situations ever including me talking about how awesome I am.

I think some of you need to step off your preconceived notions (not just about me, but about...certain others) and be willing to examine every situation on a case-by-case basis, rather than just giving me the label of 'that asshole' and people like ZV the label of 'infallible automotive encyclopedia.' Believe it or not, I can be helpful and insightful (and I was under the impression that I had been on at least a few occasions).

I wanted to do be done here soooooo long ago, but the derogatory comments just kept coming. Am I that jaded? Were people actually being nice in their trite criticisms? I've still yet to see valid evidence for the actual situations I described, it really has all been, except for a select few posters, regurgitation of black-and-white information without any actual thought or reasoning given to any of the points I've tried to make.

And yes, I would take up the challenge of 'drive better with worse rear tires,' so long as someone else drove the control vehicle that can't steer.

I'm still just utterly baffled by that. 'Can't steer' is a recoverable condition...a sliding rear end is not...I'm am definitely taking crazy pills, and good god are they working.

I think I've said that I don't have trouble admitting when I'm wrong- I just don't feel that's the case here. But I will offer up a large "I'm sorry" for ruffling so many feathers and dragging it on and on. It's not that I must have the last word, it's just that there are some things that I can't help but reply to...hell, I'm doing it right now.

edit to ask: was there anything 'reasonable-sounding' in the 'inflate to sidewall' thread? I'm thinking not. Forgive me if it sounds like I'm just trying to excuse an opinion you guys don't like by saying I can make a good argument. I just don't quite think I need to be lumped in with the 'sidewall' guy.

 

[jagec]

The point is that the rear end would never be facing the front, as I've never felt the need to make massive, catastrophic over-corrections or go through a turn at twice the speed the vehicle can handle.

Hit a patch of ice, hydroplane, hit a bump or dip at just the wrong time...the list of reasons why the back end might step out are as long as the list of reasons why the front end might start sliding. It has nothing to do with poor driving, and in every case having old tires makes it more likely. If you never lose traction in your life, it's a moot point anyway, and braking effectiveness arguments would favor better tires on the front. But the real world has corners.

You criticize the engineers for putting actual old and new tires on different ends of the vehicle and then driving it until they let go, but your counter-test is to put trays under the tires at each end of the vehicle and do the same? The difference between the engineering test and a real-world scenario is very slight, whereas your test is laughably dissimilar. Tires do not slide equally in every direction like a tray might, and the transition between grip and slip is much more complex. This works against the rear--if the tires start sliding sideways, you have to MOVE THE FRONT END OVER TO LINE THEM UP IN THE DIRECTION OF TRAVEL AGAIN if you want traction, whereas if the front starts sliding sideways, you can simply turn the tires just far enough in that direction to restore traction and allow maneuverability.

Anyone who has lost the rear end and had to "catch" it again without over-correcting, and a different time has taken a corner too fast, understeered, and then had to move the wheel just slightly to restore traction and braking effectiveness, can speak to the greater difficulty of recovering from unplanned oversteer, no matter which wheels are driving the car.

 

[phucheneh]

Again, thank you for an intelligent post that is not just some hateful attack on my intelligence. Really.

But your post helps clarify the problem here- we're not really disagreeing on the facts, so far as what effects these different tire configurations may have. But past that, it just seems like people are so stuck in this idea of 'massive, catastrophic oversteer' vs 'slight, correctable understeer.' It's apples to oranges. And we're still on the topic of 'what happens in a corner when you push the car to its limits,' which was never an argument I tried to make.

The idea that tractionless front wheels can be corrected for by steering is pretty silly. You can't just line the tires up with your direction of travel and immediately regain control...even if you could, the time it takes to do that would already have you off the road or into oncoming traffic. And sometime that direction of travel might simply be beyond the limits of your steering, making your 'understeer' response actually TRIGGER this big, bad, scary oversteer.

 

[JCH13]

phucheneh, you said: "Again, this is why engineers can suck it- go draw CAD or do some math. Leave the real world testing to people who don't think in a bubble. They're so focused on gathering data that they can't be bothered to think about what everyday driving actually consists of. Gee, so glad you got such a clear result from your empirically worthless test."

I found that comment to be incredibly ignorant, derogatory, and downright offensive.

This is also where you lost all credibility related to reasoning or logic and why you come across as a pompus know-it-all. You seem to think you know better than any automotive engineer, people who do this sort of analysis and testing professionally, have considerable higher education and training in the field of automotive engineering, and have forgotten more about vehicle dynamics than most of us will ever know.

You clearly don't know any automotive engineers, let alone any chassis dynamics engineers. I do. They're all car guys/girls. They all drive a variety of cars nearly every day and do a good bit of their own test-track driving. Also, most of them live in Michigan, which has some seriously challenging driving year-round.

You also seem to think you can drive better than the professional drivers who do the sort of testing talked about. You seem to think that somehow you'll be able to stop sudden, violent, oversteer. No one should attack every corner at 10/10ths when driving on the street, driving slow is key to driving safe. The SNAFU comes up is that one does not always know when conditions are going to change dramatically. Expert drivers who KNEW conditions would be rough would still spin, a normal driver caught completely off-guard has little chance to correct 'violent and unpredicable oversteer.' (paraphrasing from TR article). This is where understeer is your friend.

JCH13
Mechanical Engineer, EIT, Tau Beta Pi
ex-FSAE Car Designer, Fabricator, and Driver
Lemons/Chump/SCCA race car driver and builder
Car-guy and ATG regular

(since you already told me I could go suck it because an engineer, I figured I'd throw up some 'badges' on my sleeve so you had an excuse to hate me more)

 

[jagec]

The idea that tractionless front wheels can be corrected for by steering is pretty silly. You can't just line the tires up with your direction of travel and immediately regain control...even if you could, the time it takes to do that would already have you off the road or into oncoming traffic. And sometime that direction of travel might simply be beyond the limits of your steering, making your 'understeer' response actually TRIGGER this big, bad, scary oversteer.

Whereas tractionless rear tires can be lined up in a heartbeat by any moron? Regaining traction isn't always easy, but oversteer is slower to recover from and takes more skill. And getting all four wheels rotating again and aimed in the direction of travel may not instantly give you "control", but it does give you traction, which is what you use to regain control.

I'm trying to think of an understeer situation that's beyond the limits of your steering, but I simply can't. Everything that even comes close is either oversteer or a four-wheel slide.

I guess if you're driving VERY slowly along a heavily crowned road and your front wheels hit ice, they might slide sideways while your rear tires still have traction, but that's not really applicable to the current discussion.

Tell you what, the best way to get to the heart of this discussion is to give me some examples of difficult-to-correct understeer, and easily-correctable oversteer. Then we can think about whether the situation would be made better or worse by swapping the "weak" tires between ends.

 

[railer]

I'm going to be a pedant here since you're talking in absolutes (and have a retarded user picture). How do directional, staggered tires fit in to your black and white world?

I know you're not really a dope, and you can probably figure out from the context of this discussion where my comment was directed.
My G8 does have staggered wheels, and the backs would not physically fit on the front without rubbing.
I've also been known to put snows on the front, and all seasons on the rear. Why? Because I know what I have, and I needed to get up my hill in the winter, and didn't feel like buying another set of snows. Did it work for its intended purpose? Yes.
Would I want my wife or anyone else driving around like that in inclemant weather? Of course not, because it's a generally accepted bad idea to do so. Almost everyone knows this.

 

[Arkaign]

I think fundamentally the bigger issue here is that one shouldn't drive on shitty tires

I put my new ones on the front, but that's only because I never run rear ones that are freaking bald. Within a few thousand miles my fronts will be worn more than the rears anyway. Whenever they want to put the new tires on the rear, and put the older tires on front, it's a little annoying because those slightly worn tires that got rotated to the front will need to quickly be rotated back or I'll just have to replace them soon as well.

Oh, and in 20-odd years of driving I've yet to suddenly fishtail in any situation where I wasn't hooning it like a tard (mostly my teen years). I've daily driven FF/FR/FA vehicles of drastically different quality in every conceivable condition, maybe I'm just lucky. I have hit black ice once or twice, but was driving slow enough that it was no cause for alarm, no spin. I think more likely than being lucky it's just a combination of careful driving and not letting tires get so bad that you run into problems like this to begin with. I'd rather have 100% on front, 90% on rear, but once any tire starts to even hint at not being at a good level of performance I dump it, almost always in pairs. I rotate out the best of the used as my full-size spare.