Tires: Trailer tires-which ones, ST Tires, Trailer Tires

Question
I have a 19" boat on a single axle trailer.The stamp on trailer says 205-14 inch tires 35# air 3000 lbs.
The trailer has the same tires on it as when I bought it from  individual.They are 195-75-14 regular auto tires on chrome modular wheels.
Now my question is I want to replace these auto tires with trailer tires.The 195-75-14s on it squat really bad and I am afraid they will blow out.I can find 205-75-14 trailer tires but not 195s.What is the difference in the size 195 and 205.Is the height different or what?
I also find that most trailer tires are made in China now,so
I am at a loss in brands.I have read Goodyear Marathons were good in past but are not as good now.

Answer
Phil,

I'm going to take a guess that the stamp on the trailer says:  ST205/75R14 Load Range B and the 35 psi refers to the specified pressure and the 3000 is the GVWR (Gross Vehicle Weight Rating).

So doing some math:  An ST205/75R14 Load Range B has a load carrying capacity at 35 psi of 1430 # and if I am right about the GVWR, then the actual load on the tires is 3000# minus 10% (tongue weight) = 2700# or 1350 # on each tire.  That means the tire is loaded to within 94% of its rated capacity - Not Good.

BUT a P195/75R14 has a load carrying capacity of 1400# at 35 psi - EXCEPT!!  when P metric tires are used in trailer applications (or on trucks or busses) then load carrying capacity is reduced by 10%.  That mean a P195/75R14 in this situation really has a load carrying capacity of 1260 # which means if the vehicle was loaded to its max capacity, then the tires would be overloaded 7% - worse!

But as you indicate, there may be a problem with space:  An ST205/75R14 has an OD of 26.1" and a width of 8.0", where a P195/75R14 has an OD of 25.5" and a width of 7.7".

So I think you are right to be concerned about the use of the 195's, but it is fairly common for trailer manufacturers to use the minimum tire size - and that tends to lead to failures.  I don't know of a manufacturer of ST tires who hasn't received a lot of negative comments - and I think the source is really the skimpy nature of the trailer manufacturers.  I think they ought to be using tires at worse in the 85% range of their capacity - and in your case that means an ST215/75R14 Load Range B which has an OD of 26.7" and a width of 8.5"

-OR-

Find an ST205/75R14 Load Range C and inflate the tire to 40 psi.