Mc Laren makes a wider tire that is like 16 inches wide. I have the typical 12X16.5 and they are terrible in soft ground. I have not tried the wider tire, but I would try before buying. I bet they are about 4K.
The Hulk tires are Galaxy tires. There are other L-4 and L-5 tires that are good but less expensive than the Galaxy tires. I would go with these tires before going solid. Solid tires are great for demo but really suck when your in the dirt, at least the airless tires suck, I have never run the foam filled.