Elkotrailrider is right, tire wear depends greatly on the terrain your riding in. Bighorns last a little longer if you running in rocky jagged conditions than say a Terracross, because the lugs on the bighorn are larger- bigger and have less sipping witch makes them hold up a little better to rocky trail conditions.
We are trying out some of the new 8 ply sidewall tires from GBC, stronger side walls for UTV applications. Less chance of a sidewall problem. After some more testing I'll let you know how their working out.