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/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.

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.