We have a one story rambler, two bed one bath, built in the 50s, and it has a boiler system - hot water, cast iron radiators, expansion tank in ceiling in the basement.

It heats the house well, very even and fast. What I'm wondering about is if the pressure is normal. It sits at 8psi cold, and when it runs it only runs up to 10psi.

I keep reading that it should be at 12psi cold, but that seems to be the standard for a two story house? We just have the one story and baseboard rads, so the water doesn't need to rise that high. Should we add more pressure to make it 12psi? Or is 8 ok in our situation?

you need .43 PSI to lift the water up 1 foot. so 10 PSI will lift the water over 20 feet. you are fine..
the pressure has nothing to do with the heat except to lift the water to the highest point needed...

So if it sits at 8psi cold it's fine as is? I had someone tell me to add until we sit at 12psi cold, but from everything I'm reading that's standard for a 2 story house.

8 PSI is plenty for a one story house. if you bleed the air out of the radiators and water comes out of the bleeder, that is all you need.

Let's say you DO have a two story house... are there any pros and cons of having the pressure at 15-16psi instead of 12-13?

Would having a little more pressure add any additional wear to a circulator or any other parts... or is that thinking crazy now?

the pressure reducing valves i use come factory set at 12-15 PSI. i rarely change the setting. a few pounds difference one way or another does no harm..