The difference between a 10 ply and an 8 ply is the load rating. Are you carrying a load that requires a 10 ply tire?
A piece of advice my father gave me many years ago.....there's many places to go cheap, but buy the best tires and brakes you can get.
That's been very good advice for me.....rode with the neighbor last weekend and he had a flat on his trailer.....he told me he never buys new tires for the trailer as it sits to much. Each to his own, but the last thing I want is to break down while loaded with horses.
Watch the races and you'll see tires putting more cars in the wall than anything else.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.