The Mickey T. MTXs are great tires on road...very quiet and long lasting. If you air them down, they should do well in sand as well.
If you want something more aggressive, look at the Parnelli Jones Dirt Grips. I had a set in 36x14.4 R15 and they were super quiet on road at 18psi. Their tread would be great in dirt/sand, but they are pricey.
For an all around tire, its hard to beat those darn BFG ATs.
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