I'd like to clear up a tire mis-conception...

[Dave Suesz]

Recently. there was a thread discussion concerning goldline (or wide white or redline) radial tires. There was some condemnation of these tires as none-too-safe, since they were not speed-rated, and more importantly, had no "cap" to prevent separation of the steel belts. I found it hard to imagine a company which caters to car collectors would make, essentially, and unusable tire, so I contacted them.

Their reply was:

The Speed rating on the Coker Classic and the BF Goodrich radials is an S-rating, which is 112 mph.

The steel belts have a polyester "cap" to keep them from separating. Nylon was found to be less forgiving than the poly compound we use, gives a better ride, and longer life. It also does not separate like a nylon/rayon compound can. So, there is a cap, just not a nylon one.

Patrick Moates
Coker Tire Co.
1-800-251-6336 ext 254
PatrickM@coker.com

I have never used these tires, and cannot attest to the ride or handling. I was, however, impressed with how quickly they got back to me with this information. I may consider these tires next time. I don't spend much time cruising around at 112 mph.

[Duke W.]

Re: I'd like to clear up a tire mis-conception...

If anyone has these tires I would be interested in hearing what the sidewall says about construction details. They are always listed as sidewall and tread construction. Tires usually start with polyestor or rayon sidewall plys and then are covered with two steel belts. Tires rated above "T" generally have a nylon cap belts, which is placed ABOVE the steel belts. The polyester sidewall plys go from bead to bead, but are NOT cap belts because they are below the steel belts.

Typical tire construction placarded on the sidewall for a "T" or less rated tired would be"

Sidewall two polyester plays, tread two polyester, two steel.

For a "H" or above tire"

Sidewall two polyester (or rayon) plys, tread two steel, one (or two) nylon.

Nylon capped tires are very resistant to separation. All the truck tires that separated during the Firestone tire debacle were NOT nylon capped not did they have any sort of cap belt above the steel belts. I do not know of any "H" or above speed rated tires that do not have nylon cap or edge belts or some combination of the two.

I believe that Coker misstated the construction of their S-rated goldline tire. The actual verbiage on the sidewall should correctly state the construction architecture.

Duke

[John H.]

Re: I'd like to clear up a tire mis-conception...

Duke -

From the sidewall of a (new) Coker Classic redline radial, manufactured less than a year ago:

Coker Classic P205/75R-15
Radial
M&S
Tread Plies - 2 Polyester + 2 Steel Belts
Sidewall Plies - 2 Polyester
Treadwear 500
Traction B
Temperature B
Maximum Load 1598 lbs. at 35 psi Maximum Inflation Pressure

[mike yager]

Re: I'd like to clear up a tire mis-conception...

My two year old Coker redlines say the same thing on the sidewall.

So does this mean they have the cap or not? From what Duke has said, it looks to me like they do not.

[John H.]

Re: I'd like to clear up a tire mis-conception...

Duke will respond, but I doubt if they have a cap ply; these are pretty much "cosmetic" tires. I don't drive mine "at the limit" any more and they haven't given me any trouble, so they're satisfactory for my usage. I had a set of the same tires (except they were wide-whitewalls) on my '57, and had no problems with them either, although some others haven't had the trouble-free Coker experience I have.

[Duke W.]

Re: I'd like to clear up a tire mis-conception...

Coker Classic P205/75R-15

Radial

M&S

Tread Plies - 2 Polyester + 2 Steel Belts

Sidewall Plies - 2 Polyester

Treadwear 500

Traction B

Temperature B

Maximum Load 1598 lbs. at 35 psi Maximum Inflation Pressure

No, they do NOT have a cap belt. Under "tread plys" the "2 polyester" refers to the radial plys that go from bead to bead, and "2 steel belts" are the steel belt plys. There is no cap belt and, this is typical construction for tires with speed ratings of "T" or below or no speed rating. Nylon cap belts are typical for "H" and above speed ratings.

As an example of what the sidewall would say if the tire had a cap belt, here's what is listed on the 205/60R-13 86V Toyo Proxes RA-1s on my Cosworth Vega:

"Tread 5 plys (2 rayon + 2 steel + 1 nylon)"
"Treadwear 40 Temperature A Traction A"

John - is there a "service description" immediately after the size - something like 100S? The numeric value is a code for the load capacity and the letter is the speed rating. For the CV tires I listed above the load index is 86 and the speed rating is "V".

Duke

[Jack W.]

Re: I'd like to clear up a tire mis-conception...

Damn Duke is good. I have this emerging view about redlines, goldlines, etc. and performance - if you want a real honest to goodness bias ply tire that looks circa 1965 or 1967, etc. then go with something like Coker. For my Maroon 65, I want Goldlines (an available option in 65) but I really do drive my 365 hp mid-year "like I stole it" and I don't have the cahones to step up and get judged on originality (but I try to keep it correct just the same! Except for tires it seems) so here is what I am doing - I am going to decide which high performance radial I want (these are getting hard to find in the sizes appropriate for us) and I will then order them from tire rack or some such place and have them delivered straight to Diamond Back tire. They (Diamond Back) will put a correct width gold stripe (not an orange stripe - oh wait that's another topic!) or red stripe or white stripe on any tire you send them. And that's how I plan to get nice handling, high speed rated Goldlines on my 65. No offense to Coker, they make a valuable product for the show-compete-no fast driving group I guess.

[Mike S.]

Re: I'd like to clear up a tire mis-conception...

Exactly what I did. Ordered 4 Pirelli P6000 V-rated 215-65-15s from Tire Rack and had them shipped directly to Diamondback for application of raised redlines.

The tires look great, ride great, and are safe at speeds well in excess of those I'm willing to drive.

[Mark H.]

Re: I'd like to clear up a tire mis-conception...

For those of us not in the know, who/what is Diamondback?

[Tracy C.]

Yea...the last diamondback I saw caught a load

of high brass #5 buckshot....

Doesn't sound like a good idea when discussing automotive performance tires.

tc

[Jack W.]

Re: I'd like to clear up a tire mis-conception...

Diamond Back Tire: http://www.widewhitewalltires.com/index.htm

[John H.]

Re: I'd like to clear up a tire mis-conception...

Nope - immediately adjacent to the rim flange, it has "DOT 4 F F 3 VLX 2 5 0 2", which I expect is the DOT type spec and date code.

[Duke W.]

Re: I'd like to clear up a tire mis-conception...

If there is no service description (load index and speed rating) after the size then I would surmise that the tire is not speed rated, in which case the minimum DOT test standard, which is either 85 or 93 MPH would be the standard that the tire is certified to.

I'll save the editiorial comment. I'm sure everyone can imagine my opinion of such a tire.

Back to the original post in the thread - Dave - you might want to get back with Coker and educate them on the construction and certification of the Coker Classic. If John's tires are representative of what they were refering to them they have significantly misrepresented the construction and speed rating of the Coker Classic.

Should help in clearing up a tire misconception!

Duke

[Todd H 26112]

Re: I'd like to clear up a tire mis-conception...

Dave,

There was also another thread regarding safety and original bias ply tires as well as NCRS designated modern service replacements. This thread focused on NCRS best practices and risk mitigation.

I too contacted Coker several weeks ago regarding their F70 bias ply reproduction tire and also got a fast response - they could not provide me with modern measurements such as UTQG - apparently they are able to manufacture a more or less period correct tire (visually) that does not include such modern labeling as UTQG(?). They stated that the tire met the minimum DOT speed requirement - eg. non-speed rated. They also reminded me the tire did not include any warranty probably because I had made the UTQG inquiry. I've read in books, magazines and various online discussions the tires tend to not be very round and therefore not the smoothest tire at speed but have no personal experience beyond such antecdotal reports.

In the past I had 'generally' preferred H rated and above tires like V and Z, but after reading Duke's excellent articles - it valided my gut suspicion and now have made that a hard and fast personal rule for future tire purchases. Period.

While on the topic of contacting tire manufacturers - I'll mention that I also took the time to send a note off to all 19 major tire manufacturers or brands available in the US (even Hankook and Falken) regarding the 215/70R-15 as a "service replacement tire" (per offical NCRS designation) for F70-15 tires on 1969-1972 Corvettes equipped w/ original 8" wide rims. Not a single company was willing to make such a recommendation and validate NCRS' claim. Not one.