Utah has a number of "50 inch trails" where they put up a gate that prevents larger vehicles from entering. Most ATVs will not have a problem. Most UTVs will have a problem. To my knowledge the Polaris RZR 800 and RZR 570 are the only UTVs that meet the 50 inch requirement. Even those machines will fail if you replace stock items with wider tires, doors, rock sliders, etc.
The reason for mentioning this is that in my opinion, the 50 inch trails here at the Paiute Trail System are the "most interesting" in terms of challenging riding and scenery. I am glad that when I replaced my original tires, I went with 9 inch wide Big Horns in both front and back. Otherwise, I would have missed some of the best rides I have taken to date. So far, I have cleared every gate - even the one to trail 65 where the tires rubbed both posts going through.
Lastly, I want say that the above is not meant to discourage others with larger UTVs from riding the Paiute Trail System. There are thousands of miles of trails/roads that can be ridden with lots of beautiful country to be explored. This is one of the premier areas for off-road riding in the USA.