Cobra Trailer Tires (US)

On Jul 24, 9:15�am, Eric Greenwell wrote:
jcarlyle wrote:
Hi, Eric,
Here's a link to a fairly definitive article on trailer tires:
http://www.discounttire.com/dtcs/inf...ionAnxiety.dos
As you can see, it states that trailer tires are indeed optimized for
load, and that for the same dimension an ST tire carries more load
than a P or LT tire.

I found this article on the Subaru site:http://tinyurl.com/9jesg

It varies somewhat from the Discount Tire article. I suspect neither
article fully explains what we'd like to know and I wasn't able to find
a decent third article. Two statements were particularly interesting to me:

� ST tires are designed for as soft a ride as possible so they don't
� transmit too much shock to the trailer and its contents.

That might explain why an ST tire has the same load capablity at a 10
psi lower pressure than an LT.

� Trailer tires typically employ heavier steel or polyester cords and
� somewhat lighter sidewall construction than light-truck tires, and
� trailer tires typically run lower air pressures than their truck
� counterparts. This gives ST tires good load-carrying capacity, but
� with the desired softer ride. ST tires also have the advantage of
� rubber compounds that are specifically designed to resist
� deterioration from the elements, including sunlight and ozone, during
� extended storage.

I was very surprised at the Discount Tire article giving a 3-5 year life
for trailer tires, as I've always heard they were optimized for much
longer life (time) than car tires. A tire that loses 1/3 of it's
strength in 3 years doesn't sound like one I want on any vehicle, and
I'm very skeptical of that number. I know the person quoted is from
Goodyear, but Goodyear sure doesn't say that about their trailer tires.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
� � * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Try calling John at Eastern Sailplanes. John gives a safety talk on
what he has found on trailer tires over the years at contests he
attends. Its really an eye opener as he gets many calls from folks who
have blown tires along side the road. By the way, he doesn't sell
tires, but has collected quite abit of information about them.
Basicly, after 3 years, your taking a chance on them blowing out. When
they do blow out, when your traveling, they have a tendency to also
remove the fenders. Most RV tires even come with expiration dates,
which generally run 5 years, stamped on the side of the tire. I have
noticed, as I travel accross the country during the summer, rv
trailers along side the road with blown out tires. Some of them are
fairly new, so I would use caution on what brand I would buy.
Good luck shopping for them, as I have found out, their alot of
salesman giving different stories on what fits my needs.

Greg Arnold wrote:

jcarlyle wrote:
At least we agree that using P rated tires on a trailer isn't a good
idea!

I don't understand why a P rated tire that can travel 15,000 miles a
year at 80 mph on a car would not be suitable for a trailer traveling a
few thousand miles each year at 65 mph (or, for that matter, a trailer
traveling 15,000 miles a year at 80 mph). What am I missing?

My guess is people that have problems with P rated tires are choosing
ones that don't have a high enough speed rating; i.e., "cheap" tires. I
have no documentation for this, just my observation that a lot of pilots
don't think the trailer deserves good tires, especially on trailers that
are used only a few thousand miles a year.

They may also be choosing P rated tires that don't have the load rating
of the original tire. This is particularly likely to happen if the
original was an ST tire, and they put on the same size P rated tire
without realizing it has a lower load rating.

It would be interesting to collect tire type, size, pressure, age,
trailer weight, and towing speed for 50 or so trailers, just to see what
people are doing.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Jul 22, 8:24*am, RN wrote:
The tires on my Cobra trailer from the factory are marked
185R14C8PF (102/100N)LT

They appear to be GT Radial Max Miler X
Load Range D 1875 lb at 450KPA 65# cold


Try tirerack.com - they have Kumho trailer tires that match what you
have. I've used their semi trailer tires and found them to be
acceptable, but I don't have any experience with the smaller ones.
They list them for $ 80.00 each plus shipping.

Ray Warshaw
1LK

I'm in this game too -- trip to Uvalde coming up, cracks in the
sidewalls. Warning for others: two tire stores in a row have refused
to put car tires on a trailer, and there is no such thing as a 185 70
R 13 trailer tire. Tirerack.com and local gas station here we come.

Note Cobra also has a new maintenance sheet on their website
emphasizing adjusting the brakes, inspecting the hub, and inspecting
the brakes and replacing the shoes occasionally. John Murray
encourages me to do this. Boy, it's going to be a fun weekend, but
better than a blowout halfway to Uvalde.

John Cochrane BB

BB wrote:
I'm in this game too -- trip to Uvalde coming up, cracks in the
sidewalls. Warning for others: two tire stores in a row have refused
to put car tires on a trailer, and there is no such thing as a 185 70
R 13 trailer tire.

But there is a 175/80 13 trailer tire. Slightly bigger diameter, but
that gets the back of the trailer a little higher, so you don't drag as
often.


Tirerack.com and local gas station here we come.

Note Cobra also has a new maintenance sheet on their website
emphasizing adjusting the brakes, inspecting the hub, and inspecting
the brakes and replacing the shoes occasionally. John Murray
encourages me to do this. Boy, it's going to be a fun weekend, but
better than a blowout halfway to Uvalde.

John Cochrane BB

I suspect that many of the failures involve heat build up due to low
inflation. A slow leak will do it.

It's a good idea to use an infrared spot thermometer to "shoot" the tire
tread and bearing hubs at each stop. Do it on the tow vehicle tires too.
This may well provide advance notice of a slow leak or overheating bearings.
They are available from about $10 (Harbor Freight and with a 1/1 spot) on
up - - much more expensive when the heat range goes beyond 1000 degrees or
so.

For road tires, you should be seeing 200 F, so a high heat range meter
isn't all that important.

When checking tire temperatures, expect to see higher temperatures on the
leeward side, the sun lit side, or the lower side of a cambered road. With
even inflation, usually the spread won't exceed 30 to 40 F (but I seldom
drive over 60 mph so YMMV).

bumper
zz
Minden