Hi,

I am looking for some help in how to find the correct tire size for my 1986 Trail et baronII horse trailer...the tires on the trailer are not the original tires....and I think they may not be the correct size, also the tires are unreadable as to what is on them now... I have not been able to find any specs for Trail ets online...any advice?

Thanks!

IIRC your trailer is the 2h straight load bumper pull?

I know a lady who has a 2005 model, it has   ST205/75R-15  on it.  Those tires are appropriate for a 3500# axle.

The ST225 tire they suggested should also be acceptable, it is the size I have on my 2h trailer.  The difference being that ST225 is slightly larger than the ST205, but should still fit under the fenders.

Load range has to do with the pressure and load a tire can carry. 

The ST225 tire can be had in several load ranges;

Load range C  50 psi  ~2150 lbs capacity

Load range D  65 psi  ~2540 lbs capacity

Load range E  80 psi  ~2830 lbs capacity

The ST205 tire is generally found in the Load range C 50 psi with ~1820 capacity.  It is intended for the 3500 lbs trailer axles, which are most likely what you have on your trailer.

Be aware that while there is technically nothing wrong with buying a tire with more load range than you need, the wheel itself will have a max psi rating that can not be exceeded.  However buying a tire with excessive load capacity can cause a rough ride and poor braking ability.

The ST225 at a load range C would be a fine choice and give more than sufficient "safety" margin for the weights you would be carrying.  For example my trailer weighs 6000 lbs, my tires (ST 225 "C") have a total limit of 8600 lbs.

It appears you have a 'somewhat' knowledgeable tire dealer available to you.  With a basic understanding of the options you have, I suspect you and the dealer can arrive at an agreeable conclusion.