Report Laser Guided Infrared Thermometer in The Pegbox Posted September 7, 2011 Right; the laser dot is much smaller than the area measured. Commonly they advertise 8:1 or 12:1 distance/spot size ratios, although I don't know how well they actually meet that spec. When I was using one of these for measuring the temps across the tread of my race tires, there was variation on the readings depending on distance. We developed a simple method to keep the distance fairly consistent. OT- Before the racing aficionados get upset, I know that a tire pyrometer is more accurate! This cheap approach got us the ability to adjust camber, toe and pressures at events.