UTV trails/campgrounds in Richfield Utah area ???

I'll second the vote for South Forty RV Park. We go there a lot with our Teryx. Their Fall Colors rally is a favorite. The owners are very helpful recommending trail routes. You won't have any trouble not being street legal. There are direct routes from the RV park to the trails on the west side and you can drive through Marysvale without concern to reach the east side trails. No problem with your tires on any of the trails we've been on. It's a great area to ride.