This might be a dumb question but I'm having trouble with inflating my tires, and checking the tire pressure....the pressure is around "27-29", if the pressure gauge is accurate but it keeps giving me a different # each time I test it, and it was the same when I borrowed my neighbour's two pressure monitors. The tires are nitrogen filled, and the TPMS went on the other night so I checked all the tires. I noticed on two of the tires the valve stem has a red rubber part inside, and on the other two it does not...don't understand why that is. I have tried to inflate the tires that are low, but they won't accept air and the pressure gauge goes beserk way past the '35psi' which is apparently the recommended value for this car. What am I doing wrong with these stock tires?

 

your valve stems are defective or broken, you need to get them replaced.

 

I just bought the car 2 months ago from the dealership brand new. Which ones would be broken? Two have the red rubber inside and two do not. Dealership would have known this when they prepared the car for sale (doing all their checks)...right?