Nylon cap on Goodyear Marathons

[Bill]

On several occasions, Padgett has mentioned the importance of a nylon cap under the tread of a trailer tire. It makes the tire tougher, and (I think) resists tread separation. Help me out here, Padgett.

At any rate, I was rummaging though the Tire Rack web site yesterday, looking at trailer tires, and under Marathons, the description reads

"Marathon Radial tires feature a rounded profile (blah blah) .... The tire's internal structure includes twin steel belts (selected sizes reinforced with nylon cap plies) that stabilize the tread ..."

Really? So I wrote to Tire Rack and asked which selected sizes include nylon cap plies. The answer just came back:

Here are the tire sizes which come with the Nylon Cap Reinforcement:
205/75R15
225/75R15
235/80R16

Perhaps this is part of the reason why I have had such good luck with the 225/75R15 Marathons, when I had such terrible luck with the OEM 14-inch Marathons. At the same time, I note that 225/75R15 size is available as a LR-C tire, and I don't know if it has the nylon ply or not.

Bill

[Padgett]

As I understand it just about everyone uses steel plies in the tread for strength but steel does not bond well to rubber. Tires are essentially multi-piece starting with the carcass (usually two ply) and then the tread layers are bonded to that.

Bias ply tires do not separate as often as radial ply tires (has to do with the angle of the plies to the carcass). Probably the most famous example was the Firestone 500 in the late '70s though their sister company, Bridgestone, has similar problems later (any more I just buy BFGs or Micelins (same company but I haven't found an ST line).

Part of the problem is the aging of tires. Back in the day I wore out a set of Wide Ovals about every three months and a new set was $100.00. Today tires last much longer. Lately I've been replacing tires more on age than wear (though I replaced the Goodyears that came on my Jeep with Michelins when the Goodyears still had about 50% tread left because I was seeing the Traction Control light a lot when it rained. Don't now). I replaced the tires on the Judge even though they showed little wear, they were 20 years old. Big (255x70x15) muscle car tires are getting hard to find, may need to go to 17s for the next set.

But back at the nylon cap. Nylon bonds well to both steel and rubber plus it adds and additional ply of strength to the tire. By adding a nylon overlay/cap/ply (all mean the same thing) the tire is made both stronger and more resistant to separation.

Could go deep into ply angles and such. Won't. Only advice: for a single axle trailer like the TM I would only consider a LRD or E and only with a nylon cap.

[mecicon]

Originally Posted by Padgett

As I understand it just about everyone uses steel plies in the tread for strength but steel does not bond well to rubber. Tires are essentially multi-piece starting with the carcass (usually two ply) and then the tread layers are bonded to that.

Bias ply tires do not separate as often as radial ply tires (has to do with the angle of the plies to the carcass). Probably the most famous example was the Firestone 500 in the late '70s

https://en.wikipedia.org/wiki/Firest...Rubber_Company While the cause was never proved, it is believed that the failure of bonding cements, used by Firestone to hold the tread to the tire carcass, may have allowed water to penetrate the tire which in turn may have caused the internal steel wire to corrode.

Differing from the case(s) of the FORD EXPLODER where the automobile manufacturer recommended lower than optimal PSI to accommodate a "softer ride."

Originally Posted by Padgett

though their sister company, Bridgestone, has similar problems later (any more I just buy BFGs or Micelins (same company but I haven't found an ST line).

Bridgestone is not a sister company to Firestone, Bridgestone ACQUIRED Firestone in 1988 making Bridgestone the Parent.

Originally Posted by Padgett

Part of the problem is the aging of tires. Back in the day I wore out a set of Wide Ovals about every three months and a new set was $100.00. Today tires last much longer. Lately I've been replacing tires more on age than wear (though I replaced the Goodyears that came on my Jeep with Michelins when the Goodyears still had about 50% tread left because I was seeing the Traction Control light a lot when it rained. Don't now). I replaced the tires on the Judge even though they showed little wear, they were 20 years old. Big (255x70x15) muscle car tires are getting hard to find, may need to go to 17s for the next set.

But back at the nylon cap. Nylon bonds well to both steel and rubber plus it adds and additional ply of strength to the tire. By adding a nylon overlay/cap/ply (all mean the same thing) the tire is made both stronger and more resistant to separation.

Could go deep into ply angles and such. Won't. Only advice: for a single axle trailer like the TM I would only consider a LRD or E and only with a nylon cap.

[Bill]

Originally Posted by Bill

I note that 225/75R15 size is available as a LR-C tire, and I don't know if it has the nylon ply or not.

I just looked at my Marathon ST225/75R15 tires. On the sidewall it says
"Load Range D
Tread 5 plies - 2 polyester cord + 2 steel cord + 1 nylon cord
Sidewall 2 plies polyester cord."
So the presence of the nylon cap in the tread area is clearly indicated. I still don't know if the Load Range C version of this tire has the cap.

Bill

[Padgett]

May be rong but I do not know of a C rated tire that has a cap. OTOH if you want to run a D tire at 50 psi that is fine just the load rating would be the same as a C.

Guess I should have said that Bridgestone and Firestone are the same company now. But the Uniroyal (low line), BFG (mid line), and Michelin (high line) are the same company also.

[gonzo628]

Anyone know if Carlisle 225/75R15 has the nylon cap.

[Padgett]

Catalog is here but they never really say so I doubt it. They have three 225/75R15s in C, D, and E range (Radial Tire RH) on page 41. They use advertising non-specs like:
"DuraTrail™ Technology
Increases the integrity of the tires performance in challenging environments by incorporating ultra high strength steel belts with micro-fiber reinforcements."

They do mark these as "ST" tires and describe them on page 86. Again no mention of a cap or overlay.

See here for a tire that has the overlay. If you can see the tire, it will be on the sidewall. And eat my words, there is a LRC with a cap (ST205/75R15) now.

Personal opinion, ST225/75R15 LRD if you have the increased clearance and ST205/75R15 LRD if not.

ps Tire manufacturer and location is the first two letters after the DOT.

pps For a 15" tire, I'd want at least a 6" wide rim (stamped on the rim somewhere along with the manufacturer).

[Bill]

Originally Posted by Padgett

For a 15" tire, I'd want at least a 6" wide rim (stamped on the rim somewhere along with the manufacturer).

Agreed, and a 6" rim is standard on TMs.

Way back in the mists of time, RockyMountainRay, our original towing guru, put his new 15" tires on 7" rims, thinking it would be even stronger. Turned out to be a disaster - too wide, and rubbed badly. I recall that he had to do a mod to the shape of the fender skirt, using a heat gun.

Bill

[Padgett]

Have been avoiding discussion of wheels and offset/setbacks. For a trailer there is no need and unlike the UK we do not have caravan races here (OTOH there are those who will race anything. Once I took a dump truck to an economy run - scoring was on a weight index - next run they outlawed diesels - have always enjoyed pushing rules.)

For any reasonable trailer tire a normal trailer 6" wheel is fine, no need to consider camber aspects under high gee loading - where wheel width equal to the sidewall aspect becomes important - for spirited street wheel width equal to the tread width is fine.

A conventional 15x6JJ trailer wheel like a Dexstar is 5x4.5" (5x114.3mm) bolt circle and has a zero offset which means the bolt circle is centered on the wheel like a RWD car.

It is possible that a wider wheel would need a positive offset (wheel sets in further on the hub) to clear the skirt but there is no reason to use anything wider than a 6" rim width. Could spend a few hours on the subject, just know that most tires have a recommended rim width and high aspect (75 vs 30) tires are generally designed for narrower rims and most that I've seen of ST tires from 205 to 235 call for a 6" rim. Less and at max pressure you may wear the center of the tire.

If anyone really wants to know, most Ford rims are 5x4.5 but a trailer hub center ('nother subject we have not gotten into) is generally 3.19" (81 mm).

And really no need to get into my ongoing work on unladen understeer.