I am needing new tires on my 1977 WW 4 horse stock trailer. Can someone please let me know what tires I will need? 17', GVWR 6800# GKWR 5000 BF, REAR 5200#. The tires that are on it say-LOAD RANGE C; 7.00-15LT bfnv 2jk277; 4 ply .. I just need a little help putting correct/good tires back on it. Thank you