From a little research, there is no DOT or RMA or other Speed rating
applicable to ST tires. Each manufacturer of course can set their
own speed recommendations. And the majority seem to like 65 mph or
75 mph max. The basis for the ST design standard is to provide more
load capacity. In general, they have rubber compounds that are less
age sensitive, less tread depth, and stiffer sidewalls. They are
made with heavier plies and may be prone to more heat buildup
everything else being equal. They may wear faster but are not
designed to wear out but rather to be replaced before they "wear
out".
It is interesting to note that Goodyear also identifies a G614
Unisteel LT235/85R16 specifically for 5th wheel and travel trailer
use. The implication is that ST tires should be used in place of
P-metric Passenger Tires but that LT tires may also be used for
trailers so long as load and pressure guidelines are followed. And
since LT tires are typically designed for significantly higher
speeds even at full load, they may run cooler than ST tires at a
given speed. If I recall correctly the Michelin XPS also shows up in
common trailer use as well as Kumho 954 and a Bridgestone all-steel
radial that I don't recall the designation for - all of which are LT
not ST tires.
Tire Rack specifically says "Also consider that Special
Trailer (ST), as well as Light Truck (LT) tires are fully
rated for trailer applications. This means ST- and
LT-sized tires can carry the full weight rating branded on the
sidewalls when used on a trailer."
As to warranty issues, I see nothing in the Goodyear warranty that
addresses invalidating the warranty at 66 mph - there are abuse
exclusions such as racing and spin-up (drag racing) and overload,
but I don't think a reasonable dealer would claim a tread separation
(typically considered a manufacturing defect) was the result of
driving at 70 MPH - but neither would I be bragging about driving
85-90 mph (nor would I be driving even 80 mph sustained speed
pulling a big trailer at max load).
But all in all I would prefer to have a good LT tire with sufficient
load capacity to an ST tire with similar capacity. I've seen a lot
more ST failures than LT failures but in either case, at least we
can agree that "Overloading and/or failure to maintain correct
inflation" are significant causes of tire failure.
best, Ed
The following is from Goodyear
"What is the difference in a trailer specific tire and regular passenger tire?
Trailer tires are considered a special category in the current
global design standards of Tire and Rim. The major difference is
that trailer tires are required to carry 10% more load than an
equivalent P-metric size tire. LT type tires are actually on a
lower formula and would require a significant size or load change
to meet the trailer load requirements.
In the design process, we evaluate what works best under trailer
applications/conditions. We typically find that a narrower tread
width and a shallower non-skid (tread depth) provides a better
overall performance in a free rolling position. This is one case
where wider is not better. There are significant design
differences with these tires and this explains why trailer tires
are in a special category. In addition, that is why we recommend
using trailer designed or trailer specific tires in trailer
towable applications."
This is what Tire Rack says
There are differences in the driving requirements between the
tires on your trailer and those on the car or light truck you used
to tow it. Therefore there are distinct differences between the
way trailer tires and tow vehicle tires are engineered.
Your tow vehicle is a leader, which means traction is a key
focus in the design of its tires. Traction allows your tow
vehicle to accelerate down the road, turn around the corner and
brake to a stop. Another important consideration is tow vehicle
tires are designed for ride comfort, which is achieved in part
by allowing their sidewalls to flex.
Your trailer is a follower, which often makes tire sidewall
flexing a negative. Sidewall flexing on trailers, especially
those with a high center of gravity (enclosed/travel trailers)
or that carry heavy loads, is a primary cause of trailer sway.
Typical passenger radial tires with flexible sidewalls can
accentuate trailer sway problems. The stiffer sidewalls and
higher operating pressures common with Special Trailer (ST)
designated tires help reduce trailer sway.
Also consider that Special Trailer (ST), as well as Light Truck
(LT) tires are fully rated for trailer applications. This means
ST- and LT-sized tires can carry the full weight rating branded
on the sidewalls when used on a trailer.
However when P-metric or Euro-metric tires are used on a
trailer, the load capacity branded on the sidewalls must be
reduced by 9%. This means P-metric or Euro-metric tires with a
maximum branded load rating of 1,874 lbs. for use on a car is
only rated to carry 1,705 lbs. when used on a trailer.
Comparing the load capacities of a pair of tires of the same
dimensions fitted to a single axle trailer, ST225/75R15 Load Range
C-sized tires inflated to their maximum of 50 psi provide 4,300
lbs. of load capacity, where P225/75R15
Standard Load-sized tires inflated to their maximum of 35 psi
would be limited to 3,410 lbs. of load capacity, a total
reduction of 890 pounds.
Trailers will be more stable and pull better on tires designed
specifically for trailer use. Since Special Trailer (ST) tires
are constructed with heavier duty materials, they are tougher
than typical passenger vehicle tires. This is a plus because
trailer suspension systems are generally stiffer and less
sophisticated than automotive suspension systems.
Special Trailer (ST) Tire Speed Ratings
Industry standards dictate tires with the ST designation are
speed rated to 65 MPH (104 km/h) under normal inflation and load
conditions.
However Goodyear Marathon and Power King Towmax STR tires
featuring the
ST size designation may be used at speeds between 66 and 75 mph
(106 and
121 km/h) by increasing their cold inflation pressure by 10 psi
(69 kPa)
above the recommended pressure for the rated maximum load.
Do not exceed the wheel’s maximum rated
pressure. If the maximum pressure for the wheel prohibits the
increase of air pressure, then maximum speed must be restricted
to 65 mph (104 km/h).
The cold inflation pressure must not
exceed 10 psi (69 kPa) beyond the inflation specified for the
maximum load of the tire.
Increasing the inflation pressure by 10
psi (69 kPa) does not provide any additional load carrying
capacity."
On 3/12/2014 6:21 PM, Ryan Hill wrote:
From what I have gathered in talking to
tire professionals in the past regarding speed ratings on
trailer tires, an ST (special trailer) tire has a 65 mph speed
rating, period. Goodyear offers an STR version of their Marathon
which is rated to 75 mph, as I recall. (other
manufacturers probably also offer a higher speed rating)
An LT is a 'Light Truck' tire which is not recommended for
trailer use but can be used for lighter trailers due to the
stiffer sidewalls. I only use Goodyear Marathon's on my boat
trailers, this is based on what I've read about the quality and
performance of most other brands on the market.
I hear a lot of people mentioning multiple blowouts on their
tandem trailers when towing their 300's around. It's important
to understand that when a tire blows because it's been broken
down by excessive heat caused by under-inflation or sustained
high speed (abuse) etc. that the other tires likely are breaking
down equally and will also fail. If you blow a tire on a tandem,
you really should replace at least the other tire on that same
side because it probably sustained damage when the additional
load was applied to it alone.
Ryan Hill
Date: Wed, 12 Mar 2014 16:23:24 -0500
From: millserAT@xxxxxxxxxxxxx
To: ryan_hillc300@xxxxxxxxxxx
Subject: Re: [Chrysler300] Trailer Size?
My mistake the original post said 65 mph for ST tires not 60
mph - If thats a real limit on the safe speed for ST tires, in
my experience, I doubt that many people towing trailers
respect that limit. Around here on the Interstate, 75 is more
the norm with a trailer - 65 would get you run over by the
18-wheelers.
On 3/12/2014 4:14 PM, Edward
Mills Antique Tractors wrote:
I'll
have to go check my trailer tires tomorrow but I'll bet you
that my trailer tires do NOT have a speed rating - I'm
pretty sure the table you have found applies to Passenger
Tires or maybe Passenger and Light Truck - the only question
is whether there is a designation marked on ST trailer tires
where us stupid people can find it. If it is in fact 60 mph
what letter would that be? I, J, K? As for the manual - when
is the last time you got a manual with a trailer? I've
bought 2 new trailers and neither had any paperwork other
than the registration.
On 3/12/2014 3:18 PM, Ryan
Hill wrote:
Every tire that is DOT approved does have a
specific speed rating on the sidewall, it's designated
by a letter. A specific speed limit or warning on the
sidewall is not necessary; it is your responsibility as
the operator of a vehicle to know it's limitations. For
the vast majority of motorists who don't even care to
understand or pay any attention to these details, this
is why a reputable tire salesmen always ask how you
drive your vehicle and what you use it for. I would
suspect a manual from the trailer manufacturer
would recommend and/or warn new buyers of tire
limitations.
If I'm not mistaken, maximum tire speed ratings are
based on a sustained speed for a specific period of
time. The following is an excerpt from Tirerack.com:
L |
75 mph |
120 km/h |
Off-Road
& Light Truck Tires |
M |
81 mph |
130 km/h |
Temporary
Spare Tires |
N |
87 mph |
140km/h |
|
P |
93 mph |
150 km/h |
|
Q |
99 mph |
160 km/h |
Studless
& Studdable Winter Tires |
R |
106 mph |
170 km/h |
H.D. Light Truck
Tires |
S |
112 mph |
180 km/h |
Family
Sedans & Vans |
T |
118 mph |
190 km/h |
Family
Sedans & Vans |
U |
124 mph |
200 km/h |
|
H |
130 mph |
210 km/h |
Sport Sedans
& Coupes |
V |
149 mph |
240 km/h |
Sport
Sedans, Coupes & Sports Cars |
W |
168 mph |
270 km/h |
Exotic
Sports Cars |
Y |
186 mph |
300 km/h |
Exotic
Sports Cars |
While a Z-speed rating still often
appears in the tire size designation of these tires,
such as 225/50ZR16 91W, the Z in the size signifies a
maximum speed capability in excess of 149 mph, 240
km/h; the W in the service description indicates the
tire's 168 mph, 270 km/h maximum speed.
225/50ZR16 |
in excess of 149 mph,
240 km/h |
205/45ZR17 88W |
168 mph, 270 km/h |
285/35ZR19 99Y |
186 mph, 300 km/h |
Most recently, when the Y-speed
rating indicated in a service description is enclosed
in parentheses, such as 285/35ZR19 (99Y), the top
speed of the tire has been tested in excess of 186
mph, 300 km/h indicated by the service description as
shown below:
285/35ZR19 99Y |
186 mph, 300 km/h |
285/35ZR19 (99Y) |
in excess of 186 mph,
300 km/h |
Ryan Hill
To: hmpirish@xxxxxxxxxxxxx;
LabLoverDC@xxxxxxx;
billandmarilynallen@xxxxxxxxx
CC: jymopar@xxxxxxxxxxxxxxx;
mwl1967@xxxxxxx; Chrysler300@xxxxxxxxxxxxxxx
From: millserat@xxxxxxxxxxxxx
Date: Wed, 12 Mar 2014 14:33:48 -0500
Subject: Re: [Chrysler300] Trailer Size?
As to tires, any
restrictions on Speed should be identified in
the fine print on the sidewalls - if it is not I
would argue their negligence in not providing
such information - I know on the implement tires
used on farms, there is a limitation in
relatively large print not to exceed 25 or 30
mph or such - I thought it was a DOT
requirement.
Supposedly there are subtle differences in
rubber compounding that address the longer
service age typical of trailers. I have no-name
ST235/80R16 Load Range E tandem wheels on my
smaller trailer and Michelin XPS Rib LT235/85R16
Load Range E dual tandems on my bigger 20k pound
trailer.
Both have heavier axles than required and the
only problem I have ever had with either at
speeds to 80 mph was 2 of the original
Continental LT235/85R16 chunking on a hot day -
noticed it on all 4 front tires before tires
were a real problem (typically more side scrub
loads on front). Tires were about 5 years old -
2 were pretty badly chunked. Replaced all 8 with
Goodrich Commercial TA at closest Sams (only
close place that had more than 6 name brand
tires in stock) - Goodrich gave me NO problem
for several years and I watched close - then
they were recalled and I got the Michelins free.
I had previous similar chunking issues on OE
Continental tires on my F250 at about 4 years -
Ford dealer said common problem with them - no
warranty credit unless I replaced with
Continentals which he did not recommend!!! He
sold me Goodyears which worked well for about
30k miles til one blistered badly - again no joy
from selling Ford dealer (who incidentally has
done all service on my truck from day 1). They
also wore much faster than the Continentals.
Switched to Michelin at Sams - Very happy except
for price.
Several obvious lessons -
1. Go heavier on axles and tires than you plan
to use - its safer and relatively cheap when you
have trailer built.
2. Watch all tires closely - and by that I mean
inflation pressures and tread for signs of
problems and sidewalls and tread for cracking.
3. Go with a readily available size, preferably
in a name brand (not Continental - personal
thing - see above) - I like Goodrich &
Michelin based on both performance and how I was
treated in recall.
4. I don't know about what tires normally go
with 5200 pound axles, but presumably its at
least ST235/80R16 Load Range D (3000 pounds @ 65
psi) or LT235/85R16 Load Range E (3042 pounds @
80 psi) - I'd stay with one of these as they are
reasonably common.
5. Personally I would go with the LT rather than
the ST because they are more readily available
(and don't have any question of Speed
Limitations) - About the only name brand ST are
Goodyear - but what you will find on the road is
the mostly cheapo stuff (though not necessarily
at cheap prices).
6. Carry a good spare preferably under cover to
protect from aging.
7. Agree with use of Anti-Sway device on
bumper-pull trailers.
On 3/12/2014
12:41 PM, hmpirish wrote:
Hello
Shannon,
Two other
things to think about:
Tires -
most trailers come with ST radial tires,
to give a better ride. However, I
learned after going to the Monterrey CA
show, that ALL ST tires are speed
limited to 65 mph. "All bets are off"
with regard to replacement etc., if you
exceed 65mph - as I did going across
west Texas and New Mexico on I-40 at the
posted speed limit of 70mph. I had two
failures on one year old tires, and only
when replacing them found there was no
credit toward the cost of new tires. I
was informed of the speed limitation for
the first time, never having heard a
word from the trailer manufacturer or
the tire dealer when the originals were
replaced after fours years service.
The speed
limitation makes sense from the view of
economy and safety in general but on a
long trip where time is important, it
surely was a temptation to go the limit,
as I did. A possible solution would be
to specifiy LT tires when ordering your
trailer, as these do not have the speed
limit. They may not fit in the wheel
well of the trailer if you don't specify
that on ordering - some wells are very
"tight" to give max room inside the
trailer.
Hitch/stabilizer
system: From the beginning with my 28ft
trailer, the long distance from the
front trailer wheels to the hitch point,
created a swaying tendency - when being
passed by a large bus or 18 wheeler.
Especially at interstate speeds the air
buble ahead of the passing vehicle
would "push"
the nose of the trailer sideways, thus
the nose of my Ford Excursion (F-250
equivalent) TOWARD the passing bus/truck. This
required me to be ready to counter steer
to avoid closing toward the bus/truck.
The first
few times were startling but I quickly
adapted to this requirement and "had it
under control". I thought!
Then one
night in the drizzle, an 18 wheeler
passed me going at least 25 mph faster
than my 60mph. The sideways push was so
strong my excursion was pointed right at
the tractor's driving wheels in a
flash. I corrected back right abruptly
and found myself one whole lane to the
right of the one I had been driving in.
Had any one been in that lane I would
have caused a horrific accident.
The next
day I did my "homework" and invested in
a Hensley Arrow hitch which advertises,
and DOES, correct this problem
completely. I strongly urge anyone with
an enclosed trailer to go to their
website, hensleymfg.com, and get them to
send their information. The life you
save may be your own (or your beloved
300's)
One
additional thought specifically about 26
& 28 ft trailers, you must be
especially careful and think about the
space they require to maneuver
and/or, park in. My rig is 53 ft over
all. Many Hotel and Motel parking lots
will not handle rigs of this size.
Places to stop and eat have the same
problem, as do gas stations (my
excursion is a gas fuel V-10). Early on
I had to back out of a gas station I
thought I could pull straight through.
My wife directed traffic on the four
lane street so I could get out. Not Good for
marital bliss as you might imagine.
All the
Best 300ing,
Phil Irish
-----
Original Message -----
Sent:
Tuesday, March 11, 2014 11:54 PM
Subject:
Re: [Chrysler300] Trailer Size?
Just another late comment
regarding trailers for our Chrysler
300's. . . If by chance anyone is
considering a custom two car stacker
enclosed trailer, consider the
following: Make sure lift has capacity,
length and height clearance for 2nd
vehicle. For example, my 25 ft trailer
has plenty of room for '55 C300 on
bottom. My lift has 6,000 lb capacity,
but I failed to allow enough length for
another 300 letter car, a '56 Dodge, nor
a 300M due to improperly placed bracing
/ ramp door lift, etc. Maximize
internal height without exceeding 13' 6"
outside through creative frame /
platform / suspension design. Triple
7,000 lb axles and special trailer rated
tires provide a rating of 21,000 lbs. A
steel frame, aluminum skin 25 ft trailer
weighs approximately 8,500 lbs empty,
17,000 lbs loaded with two 300's. Such
a trailer requires a heavy duty tow
vehicle. If the tow vehicle is a
motorhome, be sure total length of
motorhome, trailer, and hitch assembly
does not exceed 65 ft in order to be
legal in California and in a few
northeastern states. I believe 102"
total width is now legal in all states,
even California. Make sure trailer is
towed perfectly level with load spread
evenly over all 3 axles.
Contact me directly regarding
specific trailer questions / concerns
/ ideas. I can share experiences over
past 12 years - some good, some bad,
some ugly.
Bill Allen
678-521-3658
__._,_.___
To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx
To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or
go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button
For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm
For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang
__,_._,___
|