Your tires are probably ST ( special trailer) tires 215/75R14 , found them in goodyear pressure/ loadcapacity list as only size in C-load with that maxload.
First nowadays 10% reserve is recomended by ( dont know exact american organisation) for tires to GAWR .
This covers unequall weight R/L , always is for TT.
And inacurate pressure reading, wich then 9 out of 10 to high given by gauge, so real pressure lower.
And possible overloaded axle at these ligtweight TT.
Combination of these factors can give more deflection then calculated for, so overheated tire-material, wich punisches by blowing tire or treath separation, mayby only after 2 years, when beginning internal cracks have builded up enaugh.
This smaller size is probably not calculated in maxload for 65 mph, as all 16 inch ST are, but also as LT for 99mph ( 160 kmph)
So a little higher max used speed then 65 mph is probbably not giving the overheated tire-material, but we cant exclude it.
Searched the 215/75R14 but only found ST,no LT , so cant compare if maxload is for lower speed given.
But GAWR being 2x maxload of OEM tires is done for linebusses too.
But those are not 100% of use loaded to GAWR as your TT is most likely.
Found also a D-load in ST with 108 loadindex is 2200lbs maxload wich would give the 10% reserve, and even a little reserve to full GVWR. But then dont use the recomended 50 psi as is max for C-load, you probably need the full 65 psi, and still things wont tremble loose from TT.
Theoretically you also then have to look if rimms are allowed for 2200 lbs, but reserves are that much, that it probably wont give failure of rimm, no caranties. And real weights on wheels where already higher probably, so the " overloading" was already there, and did not destoyed the rimms .
