i have a 78 hi-lo need to know what size the original tires were & the correct air pressure in each tire.

mine are a 13 inch tire with 35 lbs pressure mine is a 1996 21 Ft TL

ST185/80R13 inch 4 ply tires are 35 psi, 6 ply tires are 50 psi, all have a max speed rating of 65 mph and must be inflated to the max pressure on the tire to get the max speed rating. That is for a DOT approved (ST) trailer tire. Radial or bias ply can be used. Passenger car tires are not recommended for trailer use.

THANKS , the dry weight is 4000 lbs. duel axle . weight must matter right? i know more ply the better/cost more. can i do 8 ply. i mean like i don't want to over do it but when it comes to safety it makes me more confident in the hi-lo or my bronco that pulls it. if i know all my ducks are in a row,if you will.if i can get her up to par again i want to go west ,see this beautiful country we live in but want to avoid any foreseeable problems that can be avoided.hey know anything about the hitch part? as far as not sure what i need if anything like a weight dist. hitch do i need one and can you use just that or do i have to have stabilizers too. seems alright but haven't been out yet except a few short trips (relocating locally) and when i picked her up about 200 mi. trip. only problem was when some jerk cut me off. i felt it behind me then,it got a little squirrelly for a second , not sure if i need more towing equip. or perhaps because i was doing 70 mph (the thruway) or the short wheel base of the bronco. the truck out weighs the camper. truck 6300 lbs.- hi-lo -4000 lbs.so thats good.the engine's a 351 - v 8 . trailer tracks well behind it. thanks

I do use the weight dist hitch and bars, i haven't really needed the sway bars.

You are limited to what is available in 13" ST trailer tires. When I went to replace the 4ply tires on my 95T, I found that they were only available thru special order. So I oped for the 6 ply. 70 miles per hour is to fast for ST trailer tires and especially old ones, sustained high speeds for an hour or more is inviting tire failure. I can vouch for this as I had many tire failures until I found out that ST tires have a max speed rating of 65 miles per hour. The last one that failed on the 95 was a over a year ago. The tread rubber came off the tire, but before it came off completely it removed all the gray and black water pipes and valves also put a hole in the floor, it was a 2 year old Goodyear, 6 ply tire and I was under 65 mph but the tire had been ran at 70+mph for several hours the year before. I now keep my towing speed at or below 65 and since the last failure, I have not had a tire failure in about 6,000 miles on new tires, the new 2209T has the newer 15 radials that have a nylon belt added to the steel belts, hoping they are better. Don't know if it is true but the tire guy told me that all manufactures of ST trailer tires with steel belts are now adding the nylon belt.