Which tires are succeptible to flat-spotting?

[GC4lunch]

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Nylon makes a wonderful reinforcing fiber for tires, but Kevlar does not.

Kevlar tends to shatter like glass when compressed. That means the tire has to be handled carefully and more importantly, the tire can not be allowed to run underinflated!!!

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Where on earth did you acquire this misinformation?

"Fiber B," a nonwoven aramid material, was developed by Goodyear and DuPont specifically to be both a carcass and belting material for tires. DuPont applied the trademark Kevlar to it, and Goodyear had its own trademark (Flexten?).

Technically, the material was a success, and several automobile tires were made with it and marketed to the general public, who could care less. It was a marketing disaster because it lacked the sex appeal of "steel-belted," which sounded ever so macho.

Aramid/Kevlar is very resistant to stretching, so in a savvy marketing repositioning, Dupont devised sandwich composites that redirected direct impacts on a Kevlar surface to stretching vectors, and marketed the Kevlar sandwiches as a way to make "bulletproof" vests. Meanwhile, Kevlar made great inroads toward its original intended purpose, as a tire fabric, not in automotive tires, though, but in high end bicycle tires, which must be very light in weight and strong.

As an automobile tire component, aramid (Kevlar) remains a highly desirable material. However, it is a bit harder to work with than some alternatives, partially because of the very qualities that make it desirable, and it is also more expensive than some alternatives. Without a strong marketing hook, then, which it continues to lack, Kevlar and other aramid materials continue to be rarities in commercial tires. More's the pity.

 

[CapriRacer]

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.....Where on earth did you acquire this misinformation?.....

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From years of tire testing.

Many years ago, I had a project to improve the cut/penetration resistance of bias tires used on mining haul trucks - those 100 ton and up behemoths you see on "Modern Mechanical Marvels".

We used straight Kevlar cord and while the tires had incredible resistnce to cuts, from time to time we had a tire where the treads were coming off. This was traced by our chemists to the Kevlar breaking under compression, Back tracking we noticed that where we had data, the tires were underinflated compared to the rest of the vehicle fleet.

We tried using a combination of nylon and Kevlar to see if we could overcome this problem, but it didn't work and we abandonded the material.

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...."Fiber B," a nonwoven aramid material, was developed by Goodyear and DuPont specifically to be both a carcass and belting material for tires. DuPont applied the trademark Kevlar to it, and Goodyear had its own trademark (Flexten?).....

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I first heard about Fiber B in the early 1970's. It was touted as a miracle fiber and would revolutionize tire cord.

Here we are 30 years later, and the revolution hasn't started.

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....Technically, the material was a success....

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By whose standards?

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... and several automobile tires were made with it and marketed to the general public, who could care less....

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True, but the general pub;ic doesn't want tires that fall apart.

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...It was a marketing disaster because it lacked the sex appeal of "steel-belted," which sounded ever so macho....

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I don't know about you, but I think the general public understands bulletproof vests and would be impressed enough to at least try tires built with this material. After all, the marketing folks are really good with "high tech" as a marketing tool.

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....As an automobile tire component, aramid (Kevlar) remains a highly desirable material. However, it is a bit harder to work with than some alternatives, partially because of the very qualities that make it desirable, and it is also more expensive than some alternatives. Without a strong marketing hook, then, which it continues to lack, Kevlar and other aramid materials continue to be rarities in commercial tires. More's the pity.

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The over-riding reason Kevlar tires don't exist in ainstream tires is that the engineers can't make it work.

As bad as steel belts are, Kevlar belts are worse. At least with steel belts, the failure mode it isn't apparent under the microscope.

 

[alreadygone]

To elaborate of what I posted earlier, Kevlar/Amarid belt tires in the past were JUNK! Don't know why (or care). Technology to make it work is either too expensive or does'nt exist.

In the future, if a manufacturer "reinvents" this technology I'd suggest letting others guenia pig the first couple of million miles.

Bob

 

[GC4lunch]

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...."Fiber B," a nonwoven aramid material, was developed by Goodyear and DuPont specifically to be both a carcass and belting material for tires. DuPont applied the trademark Kevlar to it, and Goodyear had its own trademark (Flexten?).....
....Technically, the material was a success....

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By whose standards?

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By those of us who purchased and used aramid-based tires, I guess.

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... and several automobile tires were made with it and marketed to the general public, who could care less....

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True, but the general pub;ic doesn't want tires that fall apart.

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I have never heard of any passenger tire made with aramid falling apart because of the materials used in its construction.

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...It was a marketing disaster because it lacked the sex appeal of "steel-belted," which sounded ever so macho....

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I don't know about you, but I think the general public understands bulletproof vests and would be impressed enough to at least try tires built with this material. After all, the marketing folks are really good with "high tech" as a marketing tool.

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The bulletproof vest application of Kevlar came only after -- much later -- the first aramid-based tires had failed to appeal to buyers in tire salesrooms.

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....As an automobile tire component, aramid (Kevlar) remains a highly desirable material. However, it is a bit harder to work with than some alternatives, partially because of the very qualities that make it desirable, and it is also more expensive than some alternatives. Without a strong marketing hook, then, which it continues to lack, Kevlar and other aramid materials continue to be rarities in commercial tires. More's the pity.

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The over-riding reason Kevlar tires don't exist in ainstream tires is that the engineers can't make it work.

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You say this in the face of some excellent aramid (some of them Kevlar) tires having had some market success?

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As bad as steel belts are, Kevlar belts are worse. At least with steel belts, the failure mode it isn't apparent under the microscope.

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Several years ago, I fitted a full set of Goodyear Eagle F1 Steel tires to my car. The construction of the Eagle F1 Steel was unusual: the carcass fabric was high-tensile steel; the tread had another layer of steel and two aramid belts.

The Eagle F1 Steel tires were the best tires that I have ever run from a handling and braking standpoint. (Ironically, they were more prone than any other tires I have ever run to picking up nails in the street. Whether that was just because of more than normal construction activity on the streets I frequent, or an inherent defect in the tire design, I do not know. But it is unrelated to the failure mode you identified.)

I should gladly have purchased another set of Eagle F1 Steels when those wore out, but Goodyear by then had moved on to other tire designs, and they no longer were available.

Current tires that use aramid are the Pirelli P Zero Nero (three season) tire, and the Goodyear Eagle "ResponsEdge" tire, one a high-performance tire, the other a mainstream all season tire airmed at the Michelin Pilot HX MXM4 replacement market, which is huge, because so many popular sedans (e.g., Honda Accord, Ford Fusion, Toyota Camry) come fitted with MXM4's.

 

[CapriRacer]

Just to summarize:

My engineering experience with Kevlar tires was not favorable.

Alreadygone seems to have some usage experience, but he hasn't said what it is.

I keep thinking that in 30 years Fiber B hasn't become a mainstream fiber in tires - and there has to be a reason. By comparison, from 1960 to 1980 we went from nylon bias ply tires to steel belted polyester radials - a much more dramatic change.

 

[GC4lunch]

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Just to summarize:

My engineering experience with Kevlar tires was not favorable.

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And that is not being minimized at all. Similarly, I do appreciate that you have not minimized the experience of those of us who have had driving experience on excellent tires containing aramid fabric.

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Alreadygone seems to have some usage experience, but he hasn't said what it is.

I keep thinking that in 30 years Fiber B hasn't become a mainstream fiber in tires - and there has to be a reason. By comparison, from 1960 to 1980 we went from nylon bias ply tires to steel belted polyester radials - a much more dramatic change.

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That is easier to address. In a world awash with too much unprocessed information, the "wrong" factors sometimes win the battle of the marketplace. The example most often cited is the Beta vs. VHS battle in the first generation of consumer video tape recorders. Although Beta was a superior design to VHS in every respect (and although VHS was essentially a revival of an earlier generation design that Sony, inventor of Beta, had discarded as inferior), the first VHS machines had longer playing time per tape than the first Beta machines. Beta was capable of longer playing times, and Sony soon got longer-playing tapes to market, but the mindset had been cast, VHS took a lead, and continued to widen it, despite the format's inferiority.

Similarly, the concept of a steel belt under the tread captured the public imagination. It was a difficult -- probably impossible -- sell to convince a tire buyer who did not spend a lot of time thinking about tires except for the few minutes he was buying a replacement that any fabric could have the strength of steel. The perception that steel just had to be stronger than fabric doomed the marketing of aramid tires from the start. And it continues to be a hard sell.

Radial tires were on the road in Europe in 1948, and on American roads very shortly thereafter. (I was driving on radial tires in 1959.) But it took 24 years after 1948 before the first American-made radial tire hit the market. The delay was not that American companies had to get around Michelin's patents -- Pirelli also was selling radial tires at the time; the difficulty was that the American tire companies had to change their production lines to make radial tires and there was no public demand for radial tires to justify the retooling costs.

 

[CapriRacer]

I think we are again

 

[Quattro Pete]

To get back on topic, I tried running higher PSI as suggested. No change.

 

[rpn453]

I've never had any tires flat-spot on me. My Y-rated Michelin Pilot A/S tires on my Mazda3 are at 28 psi and they don't do it, nor did my V-rated Goodyear RS-As. All other tires I've owned have been H-rated or lower.

I wouldn't want to put up with that. I think I'd return them.

 

[CapriRacer]

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To get back on topic, I tried running higher PSI as suggested. No change.

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How much higher did you use?

 

[Quattro Pete]

I went from 35 PSI to 40 PSI. TireRack actually told me that I should not be running more than 33 PSI in my car, but the OEM placard on my door frame allows up to 40 PSI, depending on the load carried.

 

[Quattro Pete]

I thought I'd give an update on this.

I had the tires inspected at a local Goodyear dealer that TireRack directed me to. Unfortunately the dealer did not find anything unusual (not that I expected them to find something - afterall, by the time I got to him the tires were already warmed up and flatspotting gone

), and when he got on the phone with Goodyear corporate to discuss the claim, he was told that my issue is "normal" and will not be warranted in any way.

I really can't understand how street tires can become flatspotted just after a few hours of sitting in the parking lot after a casual drive (I'm not pushing the car hard at all). On top of that, with over 100 reviews of this tire on TireRack, no one mentioned flatspotting, which furthermore leads me to believe that there is an issue with my set in particular - maybe it's with even just one tire on the front axis. I will try to rotate the tires to see if my suspicion is correct.

Anyway, I turned to TireRack to see what they could do for me, considering that I've been their loyal customer for years and spent upwards of 3 grand on various products there. Disappointingly, they offered very little: a 15% discount towards a purchase of a new set of tires with free shipping. So much for their customer service. Needless to say, I think I'm done with TireRack. I am also done with Dunlop products which fall under Goodyear, AFAIK.

I'll come back to Continental next time I'm ready to buy tires, I think.

 

[rpn453]

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I think you will find that any tire with an H speed rating or higher will have a single nylon ply, and V rated and higher will have 2!

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I found one that doesn't! I stumbled across this thread after noticing my Y-rated Michelin Pilot tread uses 1 polyamide ply, along with 2 steel and 1 polyester.

 

[CapriRacer]

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I think you will find that any tire with an H speed rating or higher will have a single nylon ply, and V rated and higher will have 2!

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I found one that doesn't! I stumbled across this thread after noticing my Y-rated Michelin Pilot tread uses 1 polyamide ply, along with 2 steel and 1 polyester.

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I should have qualified this by saying "most". I also know of tires that are different than what I stated.

 

[Rand]

I had the same problem with tirerack. They wont do anything for you.

Discounttiredirect.com is a much friendly-er place.

just call on the phone and usually they will hook you up with a deal.

I blew out a snowtire and none were in stock.. they wouldnt do anything.

DTD- gave me 50% off one tire (purchased pair) and free ship.

 

[CharBaby]

I use my Pirelli P4's only in the winter time but I run them from late NOV to about May. Only in the cold do they seem to get flat spots after sitting overnight or any long perionds of time. It's so mild in fact(depending on the outside tempurature) that when I do hear/feel it and by the time I figure out that it's the tires making that thumping sound/feel, it's gone! If the temp's drop down to 0 or lower of course, I may feel the thumping more noticably and may actually take a couple of miles to smooth out. More or less PSI doesn't seem to change things. This is the only black mark that I can put on these P4's as I really love these tires.

 

[JDD]

Continentals flat spot worse than any other tire I have ever had. The two sets I had did it when it was only slightly cold and the vehicles sit for more than a day. When it is really cold, it was like driving the flintstonemobile for 20 miles. The lower end Goodyear SUV tires also flat spot in very cold temps as well.

 

[JDD]

Weird--I replied in a different thread, and it posted here. Strange---

 

[Craig in Canada]

I haven't followed this whole thread, but I do know that belt composition affects a tires vulnerability to flat spotting. I remember reading threads years ago which got specific about the different materials and which ones were better and worse for flat spotting. I wish I could find specifics but I think the belt-related discussion is bang on.

I've had various tires over the years and even within the same bracket (W,Y or Z rated summer ultra-performance e.g. Bridgestone S-02 PP, Toyo T1-S, Toyo T1R, Michelin PS2) and some were definitely better or worse than others. I don't think I've even felt a flat spot in my PS2s, for instance.

 

[Sayjac]

Originally Posted By: JDD
Continentals flat spot worse than any other tire I have ever had. The two sets I had did it when it was only slightly cold and the vehicles sit for more than a day. When it is really cold, it was like driving the flintstonemobile for 20 miles...
Dang, sounds like the DWS's I just returned after the DT 30 day ride guarantee. Bottom line, I said enough, and went with Michelin Primacy MXV4 and the ride is much improved, smooth. But I like the flintstonemobil analogy, very true.