MTB tire pressure

Question
Hi from Mexico. I have riding for a year so I've learning some things about mtb, but think have more questions since I star, so How do I know the right pressure for my tires, I know it's different depending the tire. I have 3 kinds, IRC 26x2.5 for mud and Tioga 26x1.95, for allterrain,and a generic 26x2" for street road. My weight is 152p. I almost use a 40 psi. in Front and Rear tires for the mountain, and 45 - 50 psi. for street thanks

Answer
Hey,
Sorry it took a while. I was out of town!
As for your question...look on the side wall of the tire. It will give you the recommended pressure. But, if you want to go off road, decrease the pressure. It will prevent flats and you will have better grip as more tire is on the ground.
On road you want to increase pressure to have less rollling resistance. Thats what I do and it works for me.