Beadlocks don't have to be expensive. I have no experience with beadlocks besides messing with the wheels Evan and Tommy have but there are less expensive options out there. Summit has some for about what you paid for those.

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You might be fine with those wheels if you keep them aired up pretty good but you would be limiting yourself if you ever wheel anywhere but the beach. I would either get 8" wide wheels or look into beadlocks. With a 10" wide wheel if you get any kind of sidewall flex you run the risk of pulling the bead off the rim. Trying to reseat a bead on a 10" wide sandy rim on the trail isn't fun to do. I put some 12.5 tires on 10" wide rims and I had to let them sit in the sun with some 2x4s stretching the tire out so they would even get close since I don't have a cheetah or any other fancy tire seating tools.