minerva is at westgate alabang, yup they charge 50 pesos per tire but unlimited refills. i've refilled 3 times na to get the psi na gusto ko talaga which is 34psi for my 195/55R15 tires. ok service nila
as for nitrogen itself one of the biggest advange over oxygen is that it maintains the tire pressure. as you all know, ordinary air expands an additional 4-5 psi when your tires have warmed up. you'll feel na mas matigas yung tires mo compared to when you just started the engine and drove. with nitrogen the pressure remains the same.
nitrogen is an inert gas and does not explode, maybe you got it confused with hydrogen?
sabi ng mekaniko dun 100 per tire daw... i just got a set of 4 tires from minerva last week. nga pala, may free yokohama umbrella for every two tires of yokos purchased hehehe
mazda... hehehe onga, the air we breathe is already 80% nitrogen hehehe