Don't skimp on trailer tires. They are worth whatever difference in price, and it is not much, and if you trailer lists 8 ply go with 10. They are worth the difference and will be that much safer. You have to remember, your trailer is probably around 8000lbs, and some standard car tires are definitely not rated for that and neither are a lot of light truck tires. It is like that old Fram ad, you can pay me now or you can pay me later. Paying for a good trailer tire will save you having to maybe repair the trailer due to a blowout.
2010 Zinger ZT29DS
2001 Silverado HD2500 Duramax