Tires: tire pressure/load, tyre manufacturers, japanese automobile

Question
I have a boat and trailer which weigh approx 1300kg. Single axle trailer. I am
running Goodyear 175R13LT's. They seem a bit soft even at 50psi. What is their
maximum load and what pressure should I run. I do some gravel raod driving,
are they adequate, what else could I use?

Answer
Steve,

The max load and pressure information should be listed on the sidewall somewhere.

But according to JATMA (Japanese Automobile Tyre Manufacturers Association) a 175R13LT came in 2 varieties:  a 6 Ply Rated where the max load of 605 kg occurs at 350 kPa (kiloPascals), about 51 psi, and an 8 Ply Rated (690lg @ 450 kPa = 65 psi).

That means that even under ideal situations, you should have 8 PR and inflate them to 65 psi.  

But gravel road changes the situation somewhat and the load would need to be reduced 10% - or put another way, you have to have tires with 10% more load carrying capacity:  1430 divided by 2 = 715 kg.  So it looks like you do not have enough load carrying capacity.  I think you need a bigger tire.  

The problem here is how much room is there under the fender - and I have no way of knowing that.

However, perhaps you ought to consider a larger trailer.