Where would you mount it in the tire? Would it be part of the rubber or part of the hub? Putting it in the rubber would cause problems because the tire bends in as it rotates against the ground. If it is part of the hub, you could use an IR xmtr on the outside of the tire. But be sure to balence the load or the tire will begin to shake! Remember the centrifugal/centripital forces that the tire will generate.