I am in need of new trailer tires and wheels. The trailer currently has white painted wheels (rusty) with F78-14ST tires. The F78-14ST tires and wheels I can only find on Ebay. I found another place with ST205/75D-14 tires on galvanized wheels for a great price. The only difference I can see is they are both load range C but the F78's are rated for 1780lbs and the ST205's are 1760lbs. My boat and trailer are not heavy (24 foot Sunsation and steel EZ-Loader trailer)

Can I use the ST205/75D-14 they seem to be almost the same?

Yes they are direct replacements.
Rich
cotnertrailers.com

You might want to ck out comparable 15" wheel/tire combo. This should up the rating.

Absolutely jump up to 15" or even 16" if you can. The bigger the wheel and the bigger the tire, the lower the heat. The lower the heat, the longer they last.

You can use the calculator here to see what you can fit. http://www.1010tires.com/TireSizeCalculator.asp

I would not buy wheels on eBay. They are usually VERY cheap imported crap with poor castings, out of round, and loose tolerances. IF you do, put the wheels on a balancer first before you put tires on them.

www.etrailer.com and www.championtrailerparts.com are a couple of sound trailer parts suppliers. There are others mentioned here if you do a search.

if in need i have a new 3500lb axel with eletric brakes with wheels and tires for 500

Thanks for the info guys.

Don't plan on buying from Ebay the F78-14ST seems to be an odd size and I could not find them anywhere else. Everybody seems to have the ST205-75-14 in stock.

Thanks for the link for tire sizes, I was also thinking bigger will be better. Looks like the 15in is only one inch taller so I will have to check and see if my fenders will clear them when I get home. The 15in wheels and tires are only $10.00 more each so it would be well worth the money.