we had a lengthy exchange of posts on this tire 2 months ago...
you can read user reports from folks who actually R rolling on this tire...
they all have a one common thread in their streaming experience.
it should not be surprising that the folks working for M' would not officially recommend using this tire 4 this application.
regulations, liablity issues, warranty claims and so on are all in play.
years of experience by one shop offering up there honest feedback matter...
design, construction, sizing and so on matter.
intended purpose matters.
the real question 4 each of us is WHICH set of metrics matter most?
ST tires seem to be constructed more like the early radial tires
used by the big 3 (and benz) on their sloppy rolling cars from the 70s.
they are 'roundish' in profile, perhaps made with larger cords and with a few modern improvements.
the tread pattern and compounds are multipurpose and with HIGHER uv resistance.
tire technology has mushroomed in ALL tire types EXCEPT st tires...
it would be nice to see some meaningful innovation in the ST class,
but lacking that, folks try cross purpose uses from P or LT or bicycle tires for their streams...
some of these experiments work out, others don't.
IF one really wants to use and understand the ratings it can get complicated.
load range does NOT equal load index.
E X T E N D E D (prolonged) carrying of a given load is different than briefly carry the same load.
car/truck tires are OCCASIONALLY loaded to higher levels with cornering or braking or accelerating.
trailer tires are more centrally mounted and continuously loaded.
car tires are designed for speeds up to 186 mph (300 kph).
even frantic trailer jockeys go faster than 80 mph.
when P metric tires are used for trucks or vans the 'load index' is supposed to be REDUCED
by a factor of ~10%.
>>>> do you understand THAT one specific issue ?
the M' LTX line includes a variety of tires/tread patterns...
in load indexes from 101 to 104 to 108 and with a variety of speed ratings.
your OP references 1985 lbs, so it would appear U are looking at the LTX M/S (NOT the m/s 2 or a/t 2 )
-are these 3 tire models better constructed and more rigorously tested than ST tires?
-are these 3 tire models capable of FUNCTIONing as trailer tires.
-are they used by folks with streams?
IN YOUR case (6600 lbs /4= 1650 PER tire, the trailer would be well withIN the load index for this P metric
even after reducing the 1985 lb rating by 10%.
-could this tire work on your stream.
-would it be a better built, more modern tire than the typical ST offerings?
and it would probably last for MORE MILEs and have fewer nagging issues often reported here (like side wall defects or separation)
-would it be MORE heat and speed tolerant?
the side wall is actually STIFFER
on these M' LTX series tires, when compared to ST tires.
-would you have warranty coverage IF the the vendor was made aware of HOW they are used?
so imo that tire CAN work on yer 25 and might present fewer problems that ST tires...
((no where do you mention EVER having any problems with ST tires ?))
but warranty cover would be IFFY.
finally, your claim/notion about 'softer ride' is totally baseless...
it appears u r assuming that a P metric tire at 50 psi will ride softer than an ST at 55-65 psi
that is a COMPLETELY incorrect conclusion.
just for reference,
i've got many sets of tires that are inflated to 35-40 psi
and they ALL ride much harder/firmer
than the ST tires at 65-70 psi...
and in COLD weather they ride like rocks, will the ST tires are supple in all seasons.
it great to experiment with tire options
but one really needs to understand what/why/how and WHEN it's appropriate.
or take the advice and guidance of experts...
the OTHER thread on this tire has user reports and expert reports...
that info CONFLICTs with the M' expert, probably for liablity reasons.
and it doesn't jive with the OEM stuff a/s dishes out.