Do tire dealers think EVERYBODY lacks knowledge

[y_p_w]

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Now for my 2 cents:

Adding a cap ply to a construction adds much more than would be indicated by the increase in speed rating from T to H. In fact some "experts" say that all tires should have a cap ply, because they are so much less likely to fail. Of course if you look at the test and understand what the result will mean - well...my interpretation is that folks in the great white north don't need to worry much about speed ratings S or lower, but the folks in Arizona have to be concerned because of the temperature.

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I know H is usually the point where a cap is almost always present. However - one of the more popular T-rated radials on the market is the BF Goodrich Traction T/A which I believe has one. My dad's car has T-rated BFG Premium Touring tires which have a nylon ply listed on the sidewall markings.

 

[oilnoob425]

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Boy, I hate to get in the middle of this argu....mmmm......discussion, but I have to correct some misconceptions.

Speed rating is a capability that a tire has. It is based on a test where a new tire is mounted in a fixture in a 77F temperature room and loaded against a wheel and the speed is increased in a series of steps. To pass a given speed rating, the tire must endure one hour at the rating speed. Usually this an "after the fact" kind of thing because the speed rating is usually a given in a line of tires, and the test is more like a compliance type of thing.

What this means is that old tires, ambient temperatures above 77F, something other than glass smooth roads, something more than one hour accumulated at speed are all in the wrong direction.

In other words, there is lot more than just the speed when we talk about speed ratings. And it's not an absolute!!!

For practical purposes, the tire construction is pretty much the only thing that is different from speed rating to speed rating.

HOWEVER.....most higher speed rated tires go on higher peformance vehicles and those tires have to be sized and designed accordingly.

So generally the higher the speed rating, the lower the aspect ratio, the lower the treadwear rating, the better the grip (treadwear and grip are pretty much mutually exclusive). This also means that higher speed rating, the more likely the tire is to be a summer tire.

And the reason I decided to post:

Rolling resistance is pretty much a function of 2 things: The tread compound and the amount of material in a tire, especially in the tread area.

Put another way, the tread design hardly affects the RR. But this all gets confounded by that fact that summer tires are generally thinner treaded but have a high grip (read high RR) compound, while all seasons have more tread rubber, but the tread compound is much better for RR (lower grip).

Winter tires are the worst of both worlds - lots of tread rubber and a grippy compound - and therefore high RR.

All this leads a lot of folks to think that the tread pattern grip has something to do with RR - it does not!!

Now to complicate matters further, cap plies - which are almost required for an H and higher speed rating - add bulk in the tread area and add significantly to RR.

Now for my 2 cents:

Adding a cap ply to a construction adds much more than would be indicated by the increase in speed rating from T to H. In fact some "experts" say that all tires should have a cap ply, because they are so much less likely to fail. Of course if you look at the test and understand what the result will mean - well...my interpretation is that folks in the great white north don't need to worry much about speed ratings S or lower, but the folks in Arizona have to be concerned because of the temperature.

The National Highway and Traffic Safety Adminsitration (NHTSA) studied tire failures by state and the top 5 were: AZ, CA, TX, NV, and FL. I'm not sure about the order but it was something like that. Also, this was NOT normalized for the population. Normally I include NM which I don't think made the list because of the low population.

Based on what I know, I think you absolutely have to have H rated tires in those 6 states. The further north, the less the need.

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If you are so knowledgable why don't you tell me what would be the difference between BFGoodridge Traction T/A T and BFGoodridge Traction T/A H ?

 

[rpn453]

Capriracer, good to have you in the thread. You make me think. I have a few questions relating to your post:

I understand that tread mass can change the rolling resistance, but I still don't see how tread pattern cannot. Do you have any links or documents? I've done competitive cycling, and I know that tread pattern makes a big difference on my bicycle, so why not on my car?

My winter tires have a lot of soft tread mass due to 14/32 tread depth. So this would indicate a higher rolling resistance. Where does that energy go? Doesn't it go into the tire as heat? Wouldn't that heat be more likely to make a tire fail under the test conditions?

If it is the cap ply, and the corresponding H-or-better-rating, that increases the safety of a tire dramatically, then I would think that any tire shop that doesn't believe they should sell an S-rated tire for a car that came with H-rated tires should also not sell anything below H-rated to anyone. Do they think that people driving older or cheaper cars are not worth the extra safety margin?

 

[CapriRacer]

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Oilnoob425 says…..If you are so knowledgeable why don't you tell me what would be the difference between BFGoodridge Traction T/A T and BFGoodridge Traction T/A H ?…

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If I worked for Goodrich, I just might be able to. But I don't, but I think I might be able to predict what the construction would be.

Generally T rated tires have a single nylon belt edge strip. Larger sizes might use 2, and the crossover point is about the 205/215/225 width. BTW, belt edge strips aren't noted on the sidewall.

H rated tires generally use a single cap ply (which would be noted on the sidewall), but I have seen some with belt edge strips. I have also seen some with spiral wrapped strip in a 2-1-2 where there are 2 layers over the belt edge and a single layer in the middle.

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rpn453 says………I understand that tread mass can change the rolling resistance, but I still don't see how tread pattern cannot. Do you have any links or documents? I've done competitive cycling, and I know that tread pattern makes a big difference on my bicycle, so why not on my car?….

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Passenger car tires are low pressure where bicycle tires are high pressure. That should mean that the effect of tread volume and compound are significantly decreased - but I doubt it - I'll bet there is something else going on! Perhaps the effect you are feeling in your bicycle is confounded by 2 factors.

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……. My winter tires have a lot of soft tread mass due to 14/32 tread depth. So this would indicate a higher rolling resistance. Where does that energy go? Doesn't it go into the tire as heat?…….

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Yes it does!!!

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……Wouldn't that heat be more likely to make a tire fail under the test conditions?…….

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Yes, but there is probably plenty of……...ah…….…what word to use………ah,……..,,,reserve capacity in what a given company accepts for speed capability that it hardly matters.

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…….If it is the cap ply, and the corresponding H-or-better-rating, that increases the safety of a tire dramatically, then I would think that any tire shop that doesn't believe they should sell an S-rated tire for a car that came with H-rated tires should also not sell anything below H-rated to anyone. Do they think that people driving older or cheaper cars are not worth the extra safety margin…..

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I think this is more a case of "selling" and not some attempt at some "Darwinian" intent. Besides, I don’t think sales folks are even aware of the statistics.

I have the good fortune - or is it curse? - to be able to see them and perhaps shape corporate policy as a result.

 

[oilnoob425]

i didn't mean how they constructed. i know that already. i would guess differently. what i meant what would be difference in the performance and grip, exept the fact that one will be able to go faster than the othe(that i also know already).
are you a tire engineer btw?

 

[y_p_w]

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i didn't mean how they constructed. i know that already. i would guess differently. what i meant what would be difference in the performance and grip, exept the fact that one will be able to go faster than the othe(that i also know already).
are you a tire engineer btw?

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I'll just throw the example of the last tires I bought before my current Bridgestones. The Pirelli P Zero Nero M+S had an identical tread pattern as the 3-season P Zero Nero. I called Pirelli technical support and asked them what the difference was, and they stated that the M+S version was designed to make a smaller footprint (to put more pressure on the tread) as well as an all-season compound. So and identical tread pattern isn't a sure-fire sign that the compound has to be the same.

The BF Goodrich Traction T/A is interesting. They have the 205/55R16 size in all three speed ratings. The T-rated version is listed as weighing 22 lbs, while the H and V-rated versions are listed as 23 lbs. The H and V-rated versions carry an AA traction rating as well as an A temperature rating. The T-rated version carries an A traction rating and a B temperature rating. The T-rated versions has a 620 treadwear rating while the higher speed rated versions list 440. I know in many cases these numbers are just sort of normalized among all the tire sizes of a specific model, but there's far more than just speed rating. Tire construction and performance has to be more than just about how fast someone can go.

 

[oilnoob425]

i don't see any specific to the point answers. i know allseason and summer got different compaunds. BUT THAT'S NOT WHAT I ASKED!!!!!!

and if you don't know anything for sure don't make assumptions: "I know in many cases these numbers are just sort of normalized among all the tire sizes of a specific model, but there's far more than just speed rating. Tire construction and performance has to be more than just about how fast someone can go."


what's the difference between 2 same model allseason tires(performance and touring, BFGoodridge for example) with different speed rating. besides tire construction and speed rating of course ?????????????????????

 

[CapriRacer]

Oilnoob425,

Let's compare the 2 tires:

Speed Rating.........T......H
Wear Rating.........620....440
Temperature Rating...B......A
Traction Rating......A......AA

So what's this mean?

The H rated version has better grip, but poorer wear - which is what you would expect.

Please bear in mind that speed rating is not the cause of the improved grip and decreased wear - it's what comes along because that's generally what is needed in a tire with a higher speed rating. Also, as a general rule, the tire will be a little more responsive to steering input due to an increase in the lower sidewall stiffness (which isn't something you can measure and it certainly isn't published as a rating or anything.)

Hopefully that answered your questions, but bear in mind that I don't work for Goodrich nor have I actually tested the tires, so I'm going by what is published.

 

[oilnoob425]

Finally somebody gave proper answer. I hope you did compare same model BFGodridge Traction T/A T vs BFGodridge Traction T/A H tires like I asked? If so Thank You, it makes sense now.

 

[benjamming]

oil,

You got a little worked in a couple posts above didn't you?

To answer one of your other questions, CapriRacer has posted in other threads that he is a "tire engineer". I hope this all puts you in better shape so you can enjoy today.

 

[kkreit01]

Within reason, the educated consumer should be able to pick/chose the tire they want. Costco is a great place (my favorite store), but they do not give the consumer any choice on tires. If I want to go 1/2 inch higher/lower/wider/narrower, I should be able to. If I want T speed rated instead of H, I should be able to. When will I drive 130? If my SUV came with T highway tires, I should have the choice of going to S AT tires. Tires Plus gave my that choice. Costco would not.

 

[benjamming]

I believe this is probably b/c the corporate lawyers say there is too much perceived liability and this is their way of cutting down on exposure. I personally think they should sell you any tire you want, and, to make the lawyers happy, have you sign a piece of paper acknowledging the differences.

 

[y_p_w]

OK - maybe I didn't say it (and thanks to CapriRacer for pointing it out) but there could be differences in steering/handling feel because of differences in the carcass. Maybe the slower speed-rated tires provide a smoother ride. Who know? The tire companies don't make it easy to figure this out (especially with all those normalized ratings) but that doesn't mean there aren't qualitative differences that are meaningful to the customer who doesn't achieve that speed.

 

[kkreit01]

I know that come retailers won't let you make the choice due to liability. It's all because of the Firestone/Ford Explorer fiasco....

 

[jmac]

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The National Highway and Traffic Safety Adminsitration (NHTSA) studied tire failures by state and the top 5 were: AZ, CA, TX, NV, and FL. I'm not sure about the order but it was something like that. Also, this was NOT normalized for the population. Normally I include NM which I don't think made the list because of the low population.

Based on what I know, I think you absolutely have to have H rated tires in those 6 states. The further north, the less the need.

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Thank goodness I went with an H rated tire this last time! this was along the lines of my thinking but it sure is good to see it confirmed once again. It is also why I always use load range E tires on my HD SRW trucks, in that case that is the first consideration.

 

[dailydriver]

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oilnoob,

There is more to selecting the right tire than the speed rating. An S-tire is rated for 112 mph. A P-tire is rated for 93 mph. Now I won't be going over 93 mph so why not just try to find a P-speed rated tire? Why would you not go lower than the T? A tire's speed rating is more than just telling you how fast you can travel on said tire.

P - 93 MPH
Q - 99 MPH
S - 112 MPH
T - 118 MPH
U - 124 MPH
H - 130 MPH
V - 149 MPH
Z - 149+ MPH
W - 168 MPH
Y - 186 MPH

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There is also an "R" rating (106 mph) believe it or not!

But I've only seen Nokian use it for their Rsi winter tires.

 

[alreadygone]

Actually,

As a tire dealer, I'm pretty sure most auto owners don't know s#!+ from wild honey!

Most common comments are, "nothing but the best" even when they don't need it. And overwhelmingly,,, "Man! don't ya got anything any CHEAPER???

Bob

 

[RH+G]

I also believe that the consumer should have the right to make an educated decision. Having worked at a tire shop I see the reason for not wanting to sell and mount tires with a lower speed rating than on the consumers car. Lawsuits are too easy to make and win. I would never sell a lower speed rating tire to a consumer. He can buy the tire but I wont mount it on the car. No lawsuits over here. NO SIR

 

[oilnoob425]

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oilnoob,

There is more to selecting the right tire than the speed rating. An S-tire is rated for 112 mph. A P-tire is rated for 93 mph. Now I won't be going over 93 mph so why not just try to find a P-speed rated tire? Why would you not go lower than the T? A tire's speed rating is more than just telling you how fast you can travel on said tire.

P - 93 MPH
Q - 99 MPH
S - 112 MPH
T - 118 MPH
U - 124 MPH
H - 130 MPH
V - 149 MPH
Z - 149+ MPH
W - 168 MPH
Y - 186 MPH

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There is also an "R" rating (106 mph) believe it or not!

But I've only seen Nokian use it for their Rsi winter tires.

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i have those on my mom's car. have no idea what their speed rating is.

 

[FowVay]

It's funny that the title of this thread is the exact opposite question that I ask. I wonder if tire dealers themselves have any knowledge.

My car came from the factory with 205/55-R16 tires with a load and speed rating of 91H. Every single tire store I have visited over the past 8 years and 180,000 miles has offered to sell me a tire with a load rating of 89 or 87. I mention this discrepancy to them and they tell me, and I quote: "Ahhh, those numbers don't me nothin'".

The funny thing is that it is only the German cars that seem to specify these higher load ratings on their OEM tires. I tend to shy away from Wal-Mart and Larry's used tires when in need of quality rubber. After all, there's more to it that being black and round.