Cobra Trailer Tires (US)

[RN]

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

They need to be replaced, and the local tire stores seem to be having
an issue identifying the correct replacement. A brief web search has
also been unsuccessful.

Any advice on the correct replacement, or where to find the code for
reading the markings would be appreciated.

John

[Frank Whiteley]

On Jul 22, 6:24*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
>
> They need to be replaced, and the local tire stores seem to be having
> an issue identifying the correct replacement. A brief web search has
> also been unsuccessful.
>
> Any advice on the correct replacement, or where to find the code for
> reading the markings would be appreciated.
>
> John

Assuming you're in the US and looking for an exact replacement in the
US, you might have to special order.

GT Radials get good marks in OZ and are made in Indonesia AFAICT. I'd
recommend contacting www.tiresavings.com to see if you can get them.
They carry the brand, but not that size.

Others will probably pop up with their replacements.

[jcarlyle]

On Jul 22, 8:24 am, RN > wrote:
I've been looking into this subject as well. My trailer is a 1983, and
uses 13 inch wheels. For it, the proper tire appears to be
ST175/80R13. Six ply is preferred, and if you want bias ply substitute
a D for the R. The most important letters are the ST, as this
specifies Special Trailer.

As to the make of tire, my research has shown that customers in the
USA recommended the Duro, Maxxis, and Denman. Goodyear Marathons have
variable reviews, and Carlisle (which also makes Titan) are NOT
recommended.

I also wanted to replace the wheels, as they are old and rusty.
Unfortunately they have an offset, and the 13" wheels I've found have
zero offset. Spindleberger says they use a number of different wheels
with different specifications, and so far I don't have a definitive
answer as to the wheel specs used on my trailer. I did find a local
shop that will bead blast the wheels, check for cracks, and then
powder coat them - that's probably what I'll do come the end of flying
season.

-John

> 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
>
> They need to be replaced, and the local tire stores seem to be having
> an issue identifying the correct replacement. A brief web search has
> also been unsuccessful.
>
> Any advice on the correct replacement, or where to find the code for
> reading the markings would be appreciated.
>
> John

[[email protected]]

On Jul 22, 9:16�am, jcarlyle > wrote:
> On Jul 22, 8:24 am, RN > wrote:
> I've been looking into this subject as well. My trailer is a 1983, and
> uses 13 inch wheels. For it, the proper tire appears to be
> ST175/80R13. Six ply is preferred, and if you want bias ply substitute
> a D for the R. The most important letters are the ST, as this
> specifies Special Trailer.
>
> As to the make of tire, my research has shown that customers in the
> USA recommended the Duro, Maxxis, and Denman. Goodyear Marathons have
> variable reviews, and Carlisle (which also makes Titan) are NOT
> recommended.
>
> I also wanted to replace the wheels, as they are old and rusty.
> Unfortunately they have an offset, and the 13" wheels I've found have
> zero offset. Spindleberger says they use a number of different wheels
> with different specifications, and so far I don't have a definitive
> answer as to the wheel specs used on my trailer. I did find a local
> shop that will bead blast the wheels, check for cracks, and then
> powder coat them - that's probably what I'll do come the end of flying
> season.
>
> -John
>
>
>
> > 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
>
> > They need to be replaced, and the local tire stores seem to be having
> > an issue identifying the correct replacement. A brief web search has
> > also been unsuccessful.
>
> > Any advice on the correct replacement, or where to find the code for
> > reading the markings would be appreciated.
>
> > John- Hide quoted text -
>
> - Show quoted text -

John,

I too have been investigating possible replacement tires . One
possibility I have identified may be Goodyear Wrangler HT 185R14 . I'm
not certain of the load bearing capacity tho .

ZA.

[sisu1a]

On Jul 22, 6:16 am, jcarlyle > wrote:
> On Jul 22, 8:24 am, RN > wrote:
> I've been looking into this subject as well. My trailer is a 1983, and
> uses 13 inch wheels. For it, the proper tire appears to be
> ST175/80R13. Six ply is preferred, and if you want bias ply substitute
> a D for the R. The most important letters are the ST, as this
> specifies Special Trailer.
>
> As to the make of tire, my research has shown that customers in the
> USA recommended the Duro, Maxxis, and Denman. Goodyear Marathons have
> variable reviews, and Carlisle (which also makes Titan) are NOT
> recommended.
>
> I also wanted to replace the wheels, as they are old and rusty.
> Unfortunately they have an offset, and the 13" wheels I've found have
> zero offset. Spindleberger says they use a number of different wheels
> with different specifications, and so far I don't have a definitive
> answer as to the wheel specs used on my trailer. I did find a local
> shop that will bead blast the wheels, check for cracks, and then
> powder coat them - that's probably what I'll do come the end of flying
> season.
>
> -John
>
> > 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
>
> > They need to be replaced, and the local tire stores seem to be having
> > an issue identifying the correct replacement. A brief web search has
> > also been unsuccessful.
>
> > Any advice on the correct replacement, or where to find the code for
> > reading the markings would be appreciated.
>
> > John

If your getting new rims too, ditch the finicky European 13" setup
that you can't find the correct size of and UPGRADE to a 14" or 15"
that has PLENTY of tire selection and is more robust. If you don't
live near a big city etc, order new rims online if you need to, but
you should be able to find good 14"-15" trailer tires (stiffer
sidewalls than car tires, but 6-ply truck tires are good too) locally.

-Paul

[jcarlyle]

Paul, that's a good suggestion, but I can't easily do it. If I get
bigger wheels the rear of the trailer will be too far in the air for
the tail gate to "lock" onto the ground when I remove the glider. I'm
also pretty sure that bigger wheels would interfere with the inside of
the fenders. Yeah, I could re-do the hitch and replace the fenders,
but since I can make the 13" wheels work without too much trouble, why
not?. Thanks anyway!

-John

On Jul 22, 11:00 am, sisu1a > wrote:
> If your getting new rims too, ditch the finicky European 13" setup
> that you can't find the correct size of and UPGRADE to a 14" or 15"
> that has PLENTY of tire selection and is more robust. If you don't
> live near a big city etc, order new rims online if you need to, but
> you should be able to find good 14"-15" trailer tires (stiffer
> sidewalls than car tires, but 6-ply truck tires are good too) locally.
>
> -Paul

[chipsoars]

On Jul 22, 1:52*pm, jcarlyle > wrote:
> Paul, that's a good suggestion, but I can't easily do it. If I get
> bigger wheels the rear of the trailer will be too far in the air for
> the tail gate to "lock" onto the ground when I remove the glider. I'm
> also pretty sure that bigger wheels would interfere with the inside of
> the fenders. Yeah, I could re-do the hitch and replace the fenders,
> but since I can make the 13" wheels work without too much trouble, why
> not?. Thanks anyway!
>
> -John
>
> On Jul 22, 11:00 am, sisu1a > wrote:
>
>
>
> > If your getting new rims too, ditch the finicky European 13" setup
> > that you can't find the correct size of and UPGRADE to a 14" or 15"
> > that has PLENTY of tire selection and is more robust. If you don't
> > live near a big city etc, order new rims online if you need to, but
> > you should be able to find good 14"-15" trailer tires (stiffer
> > sidewalls than car tires, but 6-ply truck tires are good too) locally.
>
> > -Paul- Hide quoted text -
>
> - Show quoted text -

When I replaced my 'four year old' (how long in storage) tires from
our 2003 Cobra because of sidewall cracks, the tire shop I went to
(local with several shops), which deals with several quality
manufacturers in sizes from scooters to earth moving equipment, was
unable to find a trailer tire to fit whatever 14" rim was on the
trailer. This was after calling around to every other distributor
within driving distance. Not to say I may not have found something on-
line, but time was of the essence.

I opted for a passenger tire (Delta IIRC) which had more sidewall and
tread plies than the OEM which was from a manufacturer in eastern
Europe I've not surpisingly never heard of. The replacements were not
a cheap tire and we've had no problem towing and have logged about 5k
miles without any swaying issues or wear at something over the
expressway speed limits. Of course, the trailer is stowed inside
reducing UV exposure, but you can be sure they will be gone at 5
years. One thing I don't go cheap on are tires on vehicles and
bicycles.

One thing not mentioned in addition to pressure - which ought to be
done before every trip, is to make sure these are properly balanced.
I think a lot of people hook and book without preflighting, but then I
learned the Army way driving HET"s with M60's.

Chip F

[Bruce]

Hi John

You are confusing wheel/rolling diameter and rim diameter.

Bigger rim with lower profile tyre might give you the same axle height as long as you keep to the same tread width. Less
sidewall height will improve swaying, and stability at the expense of transmitting more vibration, and being less
suitable to rough roads. If you do decide to change, I suggest you talk to a specialist - There are an amazing number of
permutations possible.

Bruce

jcarlyle wrote:
> Paul, that's a good suggestion, but I can't easily do it. If I get
> bigger wheels the rear of the trailer will be too far in the air for
> the tail gate to "lock" onto the ground when I remove the glider. I'm
> also pretty sure that bigger wheels would interfere with the inside of
> the fenders. Yeah, I could re-do the hitch and replace the fenders,
> but since I can make the 13" wheels work without too much trouble, why
> not?. Thanks anyway!
>
> -John
>
> On Jul 22, 11:00 am, sisu1a > wrote:
>> If your getting new rims too, ditch the finicky European 13" setup
>> that you can't find the correct size of and UPGRADE to a 14" or 15"
>> that has PLENTY of tire selection and is more robust. If you don't
>> live near a big city etc, order new rims online if you need to, but
>> you should be able to find good 14"-15" trailer tires (stiffer
>> sidewalls than car tires, but 6-ply truck tires are good too) locally.
>>
>> -Paul
>

[jcarlyle]

Hi, Bruce,

No, I wasn't really confusing tire rolling diameter and wheel rim
diameter. With trailer tires you don't get the range of profile
choices like with cars or trucks, so once you pick a wheel rim
diameter you effectively get only one tire rolling diameter.

Now this assumes that you stick with using ST tires on your trailer.
According to my research, ST rated tires are optimized for load
carrying, and an ST tire of given dimensions will carry more load
while running cooler than an LT or a P rated tire of the same
dimensions. Running cool is the key to tire longevity and preventing
blowouts and tread separation.

By the way, radial tires run cooler than bias ply tires, and they also
provide a softer ride for the load, so they are often chosen over bias
ply tires. However, some trailer designs tend to sway when radials are
used, so you've got to be careful when you make your selection.

-John

On Jul 23, 1:58 am, Bruce > wrote:
> Hi John
>
> You are confusing wheel/rolling diameter and rim diameter.
>
> Bigger rim with lower profile tyre might give you the same axle height as long as you keep to the same tread width. Less
> sidewall height will improve swaying, and stability at the expense of transmitting more vibration, and being less
> suitable to rough roads. If you do decide to change, I suggest you talk to a specialist - There are an amazing number of
> permutations possible.

[[email protected]]

On Jul 22, 5:24*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
>
> They need to be replaced, and the local tire stores seem to be having
> an issue identifying the correct replacement. A brief web search has
> also been unsuccessful.
>
> Any advice on the correct replacement, or where to find the code for
> reading the markings would be appreciated.
>
> John

I'm using Yokohama 185R-14 steel belted radial light truck tires. The
model is Y356. I drive too fast for ST tires and these have worked
well for 3 years.
Discount tire sells them for about $100/ea.

[Fred Blair]

Slow down


> wrote in message
...
On Jul 22, 5:24 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
>
> They need to be replaced, and the local tire stores seem to be having
> an issue identifying the correct replacement. A brief web search has
> also been unsuccessful.
>
> Any advice on the correct replacement, or where to find the code for
> reading the markings would be appreciated.
>
> John

I'm using Yokohama 185R-14 steel belted radial light truck tires. The
model is Y356. I drive too fast for ST tires and these have worked
well for 3 years.
Discount tire sells them for about $100/ea.

[Peter Wyld[_2_]]

At 12:24 22 July 2008, 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
>
>They need to be replaced, and the local tire stores seem to be having
>an issue identifying the correct replacement. A brief web search has
>also been unsuccessful.
>
>Any advice on the correct replacement, or where to find the code for
>reading the markings would be appreciated.
>
>John
>
>
Tyre marking decode...

http://homepage.ntlworld.com/cattermole/tyres.htm

[Eric Greenwell]

jcarlyle wrote:
>
> Now this assumes that you stick with using ST tires on your trailer.
> According to my research, ST rated tires are optimized for load
> carrying, and an ST tire of given dimensions will carry more load
> while running cooler than an LT or a P rated tire of the same
> dimensions. Running cool is the key to tire longevity and preventing
> blowouts and tread separation.

Trailer tires (ST designation) don't necessarily run cooler that LT or P
rated tires. Their optimization tends towards longer life (years, not
miles) because they typically aren't used as much or as often as car or
truck tires. They are not optimized for speed, and the load rating has
to be derated over about 65 mph.

My experience with ST tires recently led to me use LT tires instead, but
with a speed rating well above (say, 20 mph) my towing speed. The speed
rating ensures the tread has good lateral stiffness for stable towing
and plenty of margin to avoid tread separation.

--
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

[jcarlyle]

Hi, Eric,
Here's a link to a fairly definitive article on trailer tires:
http://www.discounttire.com/dtcs/infoSeparationAnxiety.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.

You're right that ST tires have a speed limit of 65 mph. If you want
to exceed 65 mph, then you do indeed need a different tire rated for a
higher speed. But from the above, you need to select a bigger
dimensioned tire to handle the load properly. I can't find the source
right now, but I read somewhere that you need to derate the load
rating of a P or LT tire by at least 20% if it's on a trailer.

-John

On Jul 23, 2:21 pm, Eric Greenwell > wrote:
> Trailer tires (ST designation) don't necessarily run cooler that LT or P
> rated tires. Their optimization tends towards longer life (years, not
> miles) because they typically aren't used as much or as often as car or
> truck tires. They are not optimized for speed, and the load rating has
> to be derated over about 65 mph.
>
> My experience with ST tires recently led to me use LT tires instead, but
> with a speed rating well above (say, 20 mph) my towing speed. The speed
> rating ensures the tread has good lateral stiffness for stable towing
> and plenty of margin to avoid tread separation.
>
> Eric Greenwell - Washington State, USA

[[email protected]]

A Yokohama Y356 size 185/R14/D load rated tire inflated to 65psi has a
load rating of 1850lbs which is plenty for a 18 meter glider/trailer.

[Eric Greenwell]

jcarlyle wrote:
> Hi, Eric,
> Here's a link to a fairly definitive article on trailer tires:
> http://www.discounttire.com/dtcs/infoSeparationAnxiety.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.

Looking at inflation charts for ST and LT tires, they do show the ST
tire having a higher load rating at the same pressure. Consider a
205/75R15 (load range C) tire at 50 psi: ST-1820 lbs; LT-1655 lbs.
Still, it's irrelevant as two LT tires give a 3300 pounds capacity, way
more than needed for all but the very heaviest gliders. Those can use
load range D tires to get a 4000 pound load capacity at 65 psi.

>
> You're right that ST tires have a speed limit of 65 mph. If you want
> to exceed 65 mph, then you do indeed need a different tire rated for a
> higher speed.

Not neccessarily: the ST tires can be used between 66 and 75 mph, but
they must be run at 10 psi higher pressure IF the tire and wheel are
rated for that (from a Goodyear Marathon ST info sheet - might not apply
to every ST tire).

> But from the above, you need to select a bigger
> dimensioned tire to handle the load properly. I can't find the source
> right now, but I read somewhere that you need to derate the load
> rating of a P or LT tire by at least 20% if it's on a trailer.

Note that the LT load ratings from the are for same for trucks and
trailers - no derating like P (passenger) tires require for use on
trucks or trailers. From a Goodyear inflation table title:

"SERVICE LOAD AND INFLATION TABLES [for]
LIGHT TRUCK METRIC TIRES - FOR TRUCKS, BUSSES, TRAILERS AND MULTIPURPOSE
PASSENGER VEHICLES USED IN NORMAL HIGHWAY SERVICE"

Finding a LT tire to fit a glider trailer may be problem. I'm using a
LT185R14 that Michelin doesn't seem to make anymore, and LT 14" tires
aren't common. Goodyear does show an LT195/75R14.

--
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

[jcarlyle]

Hi, Eric,

You've got some pretty good arguments there for using LT tires on
trailers. For me they're moot, though - you can't find LT tires to fit
13" wheels (I explained previously why I'm not changing wheel size).

And even though I have a heavy foot when driving, I hold it at 65 mph
maximum when pulling my Cobra. This board is full of too many horror
stories that happened to people pulling trailers, so I decided not to
compound my problems with speed. Thus I don't need a higher speed
rating than ST tires give me.

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

-John

On Jul 23, 6:14 pm, Eric Greenwell > wrote:
> jcarlyle wrote:
> > Hi, Eric,
> > Here's a link to a fairly definitive article on trailer tires:
> >http://www.discounttire.com/dtcs/infoSeparationAnxiety.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.
>
> Looking at inflation charts for ST and LT tires, they do show the ST
> tire having a higher load rating at the same pressure. Consider a
> 205/75R15 (load range C) tire at 50 psi: ST-1820 lbs; LT-1655 lbs.
> Still, it's irrelevant as two LT tires give a 3300 pounds capacity, way
> more than needed for all but the very heaviest gliders. Those can use
> load range D tires to get a 4000 pound load capacity at 65 psi.
>
>
>
> > You're right that ST tires have a speed limit of 65 mph. If you want
> > to exceed 65 mph, then you do indeed need a different tire rated for a
> > higher speed.
>
> Not neccessarily: the ST tires can be used between 66 and 75 mph, but
> they must be run at 10 psi higher pressure IF the tire and wheel are
> rated for that (from a Goodyear Marathon ST info sheet - might not apply
> to every ST tire).
>
> > But from the above, you need to select a bigger
> > dimensioned tire to handle the load properly. I can't find the source
> > right now, but I read somewhere that you need to derate the load
> > rating of a P or LT tire by at least 20% if it's on a trailer.
>
> Note that the LT load ratings from the are for same for trucks and
> trailers - no derating like P (passenger) tires require for use on
> trucks or trailers. From a Goodyear inflation table title:
>
> "SERVICE LOAD AND INFLATION TABLES [for]
> LIGHT TRUCK METRIC TIRES - FOR TRUCKS, BUSSES, TRAILERS AND MULTIPURPOSE
> PASSENGER VEHICLES USED IN NORMAL HIGHWAY SERVICE"
>
> Finding a LT tire to fit a glider trailer may be problem. I'm using a
> LT185R14 that Michelin doesn't seem to make anymore, and LT 14" tires
> aren't common. Goodyear does show an LT195/75R14.

[Eric Greenwell]

jcarlyle wrote:
> Hi, Eric,
>
> You've got some pretty good arguments there for using LT tires on
> trailers. For me they're moot, though - you can't find LT tires to
> fit 13" wheels (I explained previously why I'm not changing wheel
> size).

There's not much choice in the 14" size I have, either.
>
> And even though I have a heavy foot when driving, I hold it at 65 mph
> maximum when pulling my Cobra. This board is full of too many horror
> stories that happened to people pulling trailers, so I decided not
> to compound my problems with speed. Thus I don't need a higher speed
> rating than ST tires give me.

Slower is always more stable towing. You can reduce the tire heating
(and chances of tread separation) by using a higher pressure than
required for the load, as long as the wheel is rated for it.

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

I think it can be done safely in some cases. For example, choosing a
tire with plenty of load margin (say, more than 20%) and running it at
the maximum rated pressure, and towing at 60-65 mph.

Going to a larger rim diameter and lower aspect ratio tire (to maintain
the same outside diameter) with a high speed rating has also been
successful. The lower aspect ratio improves the stability and the high
speed rating (say, at least 20 mph over the towing speed) keeps the tire
cool.

The above might be suitable for your situation, if you can find 14" or
15" rims that fit your axle.


--
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

[Greg Arnold[_2_]]

Eric Greenwell 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?

I am presently needing new trailer tires, and need to make this choice.
The tire place has Carlisle trailer tires, which seem to have a lot
of negative comments on the internet. Anyone have personal experience
with these tires?


>
> I think it can be done safely in some cases. For example, choosing a
> tire with plenty of load margin (say, more than 20%) and running it at
> the maximum rated pressure, and towing at 60-65 mph.
>
> Going to a larger rim diameter and lower aspect ratio tire (to maintain
> the same outside diameter) with a high speed rating has also been
> successful. The lower aspect ratio improves the stability and the high
> speed rating (say, at least 20 mph over the towing speed) keeps the tire
> cool.
>
> The above might be suitable for your situation, if you can find 14" or
> 15" rims that fit your axle.
>

[Eric Greenwell]

jcarlyle wrote:
> Hi, Eric,
> Here's a link to a fairly definitive article on trailer tires:
> http://www.discounttire.com/dtcs/infoSeparationAnxiety.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" at www.motorglider.org

[[email protected]]

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/infoSeparationAnxiety.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.

[Eric Greenwell]

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

[Raphael Warshaw]

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

[BB]

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

[Greg Arnold[_2_]]

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

[bumper]

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