Congratulations on the purchase!
The choices for trailer
tires are ST or LT, never P (passenger) radials. Since they don’t make LT tires in a 13” size, that leaves ST as a direct replacement. For a larger trailer like a 17’
Burro, look for a minimum D load rating. Carlisle and Maxxis are well-regarded brands. Goodyear Endurance is one of the best, but they don’t make a 13” size.
If you have clearance, you could go to 14” or 15” wheels and tires, but if not, you’ll need to wait until you’re ready to do an
axle swap. The larger sizes open up a lot more tire choices, including LT tires and heavier load ratings if desired. However, now that they make D-rated tires in a 13” size, it’s something you can defer if you want.
Tongue
weight should be 10-15% of total trailer weight. 12% is a good target. Only way to know for sure is to weigh it on a certified auto and truck (CAT) scale. Until then, if you have two full LP tanks on the tongue and an otherwise empty trailer, you’re probably okay until you can get it to a scale. Most trailers are designed to be properly balanced when empty. Sway is affected by speed, so approach highway speeds cautiously on your first tow with a new-to-you trailer.
If you’re not sure, if your tongue is empty, or if it starts getting squirrelly at higher speeds (tendency to low amplitude tail-wagging), adding additional weight up front is a quick solution. If it has a rear-mounted spare, you could take it off and toss it on the floor at the front of the trailer.
As to the bearings, ask the seller when they’ve last been done. If it’s within 2-3 years, you’re probably good for a short trip to get home. Do stop and check temperature at 20 and 50 miles during your initial tow. Bring the back of your hand to the hub. They should be warm but not too hot to touch. Dragging
brakes can also generate heat. Either way, excessive heat requires immediate attention.