nothing wrong with a 30$ tire 18.5 x 8.00 x 8" and 16.5" x 8.0 x 8"
The King fox tires started at ?? $20 or so I think
then the 12"x 21"x 8" were about $30 too but now $50 to 70$
I have used all the above tires sizes and all work well.
The later two will give you the ultimate in flotation for soft ground- mud,sand ,water and snow.
I have never hear of one failing being a 2 ply versus a 4 ply.
Just a thought, check with your local tire supplyer, they can get any tire you can and if it comes from one of their normal suppliers and they just include it in another order, you can dodge the shipping charges. Might end up cheaper for you. I've done that myself. Take care, Jim Chuk