Tire pressure inspection hole
A laser pointer works well to locate the hole. With the pants off, aim the pointer at the correct angle to reach the tube stem. Then install the pant without moving the pointer or the plane, and mark your hole location on the pant.
I eliminated the tire pressure inspection hole for a few reasons:
-new butyl or "air stop" tubes don't leak like the old rubber tubes, and seldom require topping up
-I can determine correct tire pressure by running my finger between tire and bottom of wheel pant. I built the pants with a finger width tolerance to the tire, so if the pressure is low, the gap is too narrow
-I pull the pants at 50 hour intervals to check the brakes anyways; and check pressure at that time (they don't leak)
- if I change my mind, I can always add holes later
IO-375, Catto, Electroair, Skyview