A tire parameter monitoring system has a plurality of sensor units for monitoring tire parameters, with each sensor unit mounted with a different vehicle tire. The housing is preferably made from a material which burns cleanly and has improved ablative qualities to prevent accelerated arcing within the plasma generated by the housing during high energy periods. It is especially suited for multi-pass print modes since each row has a balanced number of pixels, and there are no rows which have no on pixels. The controller determines an average number of signals relative to distance and compares the average number to a current number of signals relative to distance. A cable connector may be mounted to the movable connector member to move therewith as a unit. An annular stirring member is arranged in the chamber projecting from an inner periphery side of the external cylinder member inward toward a chamber wall face on the internal cylinder member side form a clearance therebetween.