Tire ply description as listed on sidewall

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I wish the major tire retailers, or the manufacturer's web pages, would provide (publish) the ply information that is shown on their tire sidewalls.

I know that sometimes Tirerack list some information about the internal tire construction but it isn't consistent and often incomplete.

I was looking at physical examples from Goodyear, Toyo, Kumho, Douglas, GT Radial. All were "S" rated tires except the GT Radial which was "T" rated. All of them showed:

Tread: 1 Polyester + 2 Steel
Sidewall: 1 Polyester

Of course, this basic construction seems pretty common in the everyday class of all-season "S" rated tire.

What I found of interest is the description on the sidewall of the 215/70/15 Starfire 340 ("T" rated) tires on my van. It shows

Tread: 1 ply Polyester + 2 ply Steel, 1 ply nylon
Sidewall: 2 ply Polyester

I wonder how or why they end up with 2 plies of polyester on the sidewalls but apparently 1 of these plies does not continue on around the casing in the tread area?

It would seem that any trade off in the slight amount of material savings would be offset by a more complicated design and manufacturing process to not extend that 2nd ply completely around the tire as they do the first?

From what I read, that 2nd ply does make for a stronger sidewall but I guess there is a trade-off which might include slight added cost, a weight penalty (fuel economy) and slightly stiffer or harsher ride. Any other ideas?
 
Sidewall construction plays a large roll in low rolling resistance tires that come on most new cars anymore. Soft sidewalls deform and requires more horespower to move the vehicle. Steering response is better on tires that have stiffer sidewalls. Semi trucks and trailers go a different route and use a 1 ply steel sidewall.
 
Originally Posted By: Cressida
I wish the major tire retailers, or the manufacturer's web pages, would provide (publish) the ply information that is shown on their tire sidewalls.

I know that sometimes Tirerack list some information about the internal tire construction but it isn't consistent and often incomplete.

I was looking at physical examples from Goodyear, Toyo, Kumho, Douglas, GT Radial. All were "S" rated tires except the GT Radial which was "T" rated. All of them showed:

Tread: 1 Polyester + 2 Steel
Sidewall: 1 Polyester

Of course, this basic construction seems pretty common in the everyday class of all-season "S" rated tire. .......


Just a clarification:

The construction of a tire also depends on the size. Tires with larger air chambers require more fabric. Ergo, you will find large passenger car tires with 2 body plies, while small passenger car tires only have one.

There is a point (size) where it changes from one body ply to 2, and that varies not only by the manufacturer, but by plant of manufacture (depending on the exact blend of fabric available at that particular plant).

I suppose retailers like Tire Rack could look at each shipment and publish what they find - just like they do for country of origin (That varies as well!!) OTOH, it is a lot of work as EVERY shipment and EVERY size in a shipment would need to be looked at (Small letters, etc.)

Originally Posted By: Cressida
........ What I found of interest is the description on the sidewall of the 215/70/15 Starfire 340 ("T" rated) tires on my van. It shows

Tread: 1 ply Polyester + 2 ply Steel, 1 ply nylon
Sidewall: 2 ply Polyester

I wonder how or why they end up with 2 plies of polyester on the sidewalls but apparently 1 of these plies does not continue on around the casing in the tread area? .....


It is rare, but I have seen this before.

Instead of the turnup ending in the lower sidewall area, it ends under the belt - and according to the regulations, that makes the sidewall have 2 plies and the tread area only one!

Originally Posted By: Cressida
......... It would seem that any trade off in the slight amount of material savings would be offset by a more complicated design and manufacturing process to not extend that 2nd ply completely around the tire as they do the first?

From what I read, that 2nd ply does make for a stronger sidewall but I guess there is a trade-off which might include slight added cost, a weight penalty (fuel economy) and slightly stiffer or harsher ride. Any other ideas?


I think what that arrangement is trying to do is to put the ply ending in a place where it is unlikely to cause trouble. It is not unheard of that a separation can start at the edge of the turnup. May be they have had some issues in the past.

At the same time, that would increase the strength of the tire in an area where it is advantageous. That is, it might be that they would have ordinarily used 2 body plies in this size, but since the belt is strong enough, they don't need the second ply under the belt.

Originally Posted By: skyactiv
Sidewall construction plays a large roll in low rolling resistance tires that come on most new cars anymore. Soft sidewalls deform and requires more horespower to move the vehicle. Steering response is better on tires that have stiffer sidewalls. Semi trucks and trailers go a different route and use a 1 ply steel sidewall.


Actually, plies play a small role in RR. Sidewall stiffness mostly comes from the inflation pressure and small differences in sidewall construction don't matter much.

What truly matters for RR is the tread - compound and volume. Thick, knobby treads aren't good for RR, nor are high grip or good wearing rubber compounds.
 
Thanks for that helpful information CapriRacer.

Can you tell us a bit more about the "turnup"?

Is that what is described of the area; or how the plies wrap around the wire bead area and terminate within the rubber compound? Are you suggesting that a sidewall ply could also terminate under the tread or shoulder area - and if so does it have to wrap around something to help secure it, like what I envision it wrapping around the bead?
 
Originally Posted By: Cressida
Thanks for that helpful information CapriRacer. .......


Quite welcome.

Originally Posted By: Cressida
.......Can you tell us a bit more about the "turnup"? ......


Sure

Originally Posted By: Cressida
...... Is that what is described of the area; or how the plies wrap around the wire bead area and terminate within the rubber compound? .......


Both

Originally Posted By: Cressida
........ Are you suggesting that a sidewall ply could also terminate under the tread or shoulder area ........


Yes, that is what I am suggesting - although I see potential problems with that.

Originally Posted By: Cressida
....... - and if so does it have to wrap around something to help secure it, like what I envision it wrapping around the bead?


Yes, I think the ply has to wrap around the bead.
 
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