Q: Special tires for '99 Camry LE V6?

Car Guy wrote:


What they actually said was "But more precise handling and better heat resistance at normal highway speeds are the important reasons that high-performance tires, especially H-speed-rated, performance all-season versions, are quickly redefining the tire market."
I certainly am not arguing that high-performance tires are not a good thing. I just arguing against the idea that a higher speed rating automatically implies better handling or braking performance.

I don't disagree with what was said above, but I do think it really doesn't say anything important either. I am not arguing that in many cases tires with higher speed rating are also higher performance tires. What I am arguing is that there is no direct link between the speed rating and performance in other areas. The test to verify the speed rating does not test traction or handling response. It merely confirms that when loaded to it's rated load the tire can be run at the speed associated with the rating in a laboratory test. From http://www.tirerack.com/tires/tiretech/general/speed.htm :
"Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met."
Nothing in this test says anything about braking performance or handling performance. I believe it would be relatively easy to design a tire that could meet the speed requirements while having horrible characteristics in other areas. I can see no reason why such tires would be made, but they could be.
I think we are seeing different things in the CR test report. For the ultra high performance tires (W,X,Y,Z speed rated), the braking and handling performance of the tires varied from only "good" to "excellent." The same was true of the mostly H speed rated "performance all-season tires" tested (only one was rated as poor). If you combined the two lists, it appears to me that you would be unable to pick out the ultra performance tires solely by their position in the list. The worst "H" tires would clearly be at the bottom of the list, but at the top of the list, there would be no consistent differences based solely on speed rating (or price for that matter). In fact, it looks to me that if you are trying to go for the best bang for the buck and you don't need snow traction, the H rated Bridgestone Potenza RE950 was by far the best choice at a cost of $85 per tire. It got top marks in dry traction, dry braking, wet braking, and hydroplaning resistance.
I am fully in agreement with the idea that you should purchase good quality tires for your car. Cheap tires are a sure way to ruin the ride and handling of a car. I just don't agree with the idea that buying W,X,Y, or Z speed rated tires equates to buying the best tires for a car. I am also not in agreement with the idea that tires with higher speed rating necessarily have better braking and handling performance than tires with lower speed ratings. It may usually be true, but it is not written in stone. It is merely one of many important performance characteristics.
Ed
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Yes, there is a direct link because the MANUFACTURING METHOD that is used to make the speed rating higher also makes improves handling and performance. This usually includes the use of softer tread compounds or advanced high-tech tread compounds.
You are in complete denial as to the facts stated from the above web-site.

That is precisely what I have tried to point out to you. The tests are done in the laboratory and not on real roads. A tire heats up as it flexes due to road contact and due to tread squirm on less than a perfectly smooth road surface. So the speed ratings cannot be used for real world comparison (it is wrong to say that since I never exceed 108 mph, I can safely use S rated tires), except as used on a "relative" basis (H rated tires have a larger margin of safety than S rated tires with regard to speed related damage, almost always caused by heat).
Ed, unfortunately, you don't know what you are talking about, and are just speculating based on some rather incomplete information you have received.
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Mark A wrote:

The speed rating does not depend on softer compounds. And it may be that the methods used to improve the speed rating might also improve the handling and performance, but it does not have to be true. In my opinion, the easiest way to improve a tires speed rating is to change the aspect ratio. A tire with the same design, tread style, and material, but with a lower profile, will most likely (at least in my opinion) generate less side wall flexing and therefore heat. This may allow the tire to have a higher speed rating. A clear example of this is the Michelin Energy MXV4. The P205/65R15 and the P20/60R16 have almost identical ODs, identical tread wear ratings, identical traction rating, identical tread patterns, and similar load ratings. However, one is "H" Rated and one is "V" rated. Care to guess which is which?

What facts? You mean statements like "Changing from the O.E. tire speed rating to another performance level tire will probably change handling in areas such as:" "Will probably" is a fact? I 100% agree that changing performance level will affect performance. I even agree that in most cases tires with a higher speed rating are higher performance tires, but not because it has to be true. I also agree that tires of the same size and type but with different speed ratings will perform differently but not necessarily more so than tires of the same size and type from different tire lines. It is my opinion that you are using backwards logic. As I understand it, you are saying tires with a high speed rating are automatically high performance tires with superior handling and braking performance. I don't agree this is a valid argument. If you turn it around and say most performance tires with superior handling and braking performance also have higher speed ratings, then I am in agreement. I am also willing to concede that tires of the same size and type with different speed rating will have different, but not necessarily superior, braking and handling performance.

I agree with this. However, this has nothing to do with how well a tire handles or a tires braking performance. If you are arguing that tires with a higher speed rating, all other things being equal (size, load, inflation pressure) are less likely to fail due to heat build up than tires with a lower speed rating, then I am in 100% agreement with you. However, if you are arguing that tires with a higher speed rating automatically have superior handling and braking performance, I am not in agreement.

I at least am using some facts. You merely keep repeating your opinions as fact with no support whatsoever.
Michelins definition of a speed rating - "Speed rating: An alphabetical code (A-Z) assigned to a tire indicating the range of speeds at which the tire can carry a load under specified service conditions."
I don't see any mention of different handling or braking performance based on speed rating.
Also from Michelin -
"Can I replace the tires on my car with a lower speed-rated tire? "When replacing speed-rated tires, you must use replacement tires with ratings equal to or greater than those of the original equipment tires, if the speed capability of the vehicle is to be maintained. The handling of a performance vehicle may be different when the replacement tires are not the same speed rating. Refer to the vehicle owner's manual to identify any tire speed rating restriction that could affect the operation of the vehicle."
I agree with this statement, but I also don't see where it implies that higher speed ratings imply superior performance in other areas. Different performance is not necessarily better performance.
I have said my piece. We really aren't too far apart. I think we both agree it is important to purchase good quality tires of the proper speed rating for your car. The only area of disagreement is that you imply that a higher speed rating automatically implies superior braking and handling performance. This is an insupportable assertion. I doubt that even you believe that all V rated tires have better handling and braking performance than all H rated tires.
Ed
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You are right. Probably on Mars or some alternate universe it is done differently. But on Earth, higher speed rated tires that are commercially available have better handling, cornering, breaking, emergency maneuvering, etc. This has been clearly documented and you refuse to believe it.
Give it up. You are a complete quack and a menace to society.
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Mark A wrote:

Site the documentation please. Go read the November 2003 CR article and tell me how you can make the above claim in light of the overlapping range of performance for H and higher speed rated tires. There is absolutely no hard relationship between speed rating and "handling, cornering, breaking, emergency maneuvering, etc." The relationship between speed rating and other performance characteristics is similar to the relationship between a vehicle's cost and it's overall performance. In most cases the tire with the higher speed rating will have have better performance characteristics, but it isn't always true. Likewise, higher priced cars usually have superior characteristics, but this is not always true.

Exactly how am I a menace to society. Is it wrong to recommend that tires be selected based on an overall evaluation of the performance characteristics instead of just assuming that a higher speed rating equals a superior tire? By warning people that the speed rating is only one characteristic that needs to be considered when purchasing tires? By trying to correct your misrepresentation that a tire with a high speed rating automatically has superior properties in other areas? Go back and show me where I have ever said that someone should buy low speed rated tires. Go back and show me where I have ever said that an individual should buy tires of a lower speed rating than the OE tires. In all respects, I have taken the a conservative and safe position. You have made a claim that are is supported by the facts. Calling me a "complete quack" does not make your misstatements true. You should make your point by presenting facts, not by disparaging those that disagree with you.
Ed
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In

Hahahhahhah! Ed has too much hubris to yeild to your wisdom.
--
-Philip

"Whatever is a choice will become chosen"
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But were the lists meant to be combined? Probably not. They tested different size tires for the different groups (the H-rated tires in 195/65R15 on a Honda Accord, and ultra high performance tires in some other size on a Ford SVT Focus). So, while the results were comparable within groups, they may not be comparable across groups (and tire size requirements probably mean that you may not have much choice in what type of tire to get for a given car anyway).
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Timothy J. Lee
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Car Guy wrote:

"wet traction" is separately rated by the letters, A, AA, etc.
Higher "speed" rated tires are often not better for wet traction. IOW, being V rated does not ensure better wet traction over a tire w/ H or S speed ratings.
Unfortunately, there is no rating for "sidewall stiffness". Therefore we are left w/ our own personal evaluation and opinions from other users.
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The reason for that usually has to do with tread design and tire width. V rated tires are often used on luxury cars where the tread design is optimized for quiet ride over wet traction.
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My issue with Consumer Reports is that they review a tire for a short period of time and then provide feedback. They don't make any effort to say how the tire will perform for its expected life. By this, I am referring to the fact that some tires tend to develop sidewall deformities as well as require frequent balancing to remove steering vibration.
It is one of the reasons why I like Tire Rack's customer reviews since, they may not be as technical as Consumer Reports, they can tell you how the tires faired after 20,000 miles of driving and not 200 miles of tests.
Don't get me wrong. Consumer Reports testing offers valuable info, they just need to expand on the long term view of these tires to the manner of how auto journalists from various magazines and web sites take a vehicle for 20 months and put it thru its paces and tell you how it faired. JD Power does provide customer satisfaction ratings on tires but I am unsure in the criteria they use.

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Car Guy wrote:

Consumer Reports tests what it can and/or considers important. I often find myself at odds with their findings and test methods. They are not immune from trying to construct tests to prove their particualr pet theory. I have always though their owner surveys were poorly constructed and of little value. However, for what it was, their November tire test was OK. Unfortunately it will be obsolete within months since manucturers constantly change tire models. I only referenced it as one source of information that showed there was not a direct link between speed rating and performance in other areas. The Tire Rack information is another. However, the Tire Rack information is based solely on the owner's opinions. Becasue of this it is more a measurement of handling or braking feel, than actual performance.

Their results are interesting, but they measure satisfaction, not actual measurable performance. Not that this is unimportant, but it can be misleading.

JD Powers runs a popularity contest. JD Power measures preceprtion which may or may not reflect reality (see http://www.jdpa.com/news/releases/pressrelease.asp?ID 03123 and http://www.jdpa.com/news/releases/pressrelease.asp?ID 03081
The results available for "free" only address satisfaction buy brand. Since all brands include a wide range of products, it is hard to make any decisions based solely on the information provided for free.
Ed
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I think this argument over speed rating vs. tire capabilities is becoming more like a law case. You have the Crown (Mark A) and the Defence (C.E. White). At the end of the mud slinging, I wonder who will admit defeat.
Not to pick sides, but from everything I have heard and read, higher speed rating tires tend to be more sticky (temp/tire ratings) and thus offer better braking and precise handling (due to increased sidewall stiffness). Also, as mentioned in this post, these high speed tires are sold at premium prices and add things like silica and other things to promote improved grip.
Now, to compare wet traction, tread design plays a HUGE part in that. A V rated tire may be more sticky in dry weather, but if it does not have evac chutes, the tire will not have adequate contact with the road and cause hydroplaning. Here tire design, not speed rating is important.

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