Hi guy's
If I change the pulley on my power steering pump to a smaller one will this help me turn bigger tires at slow speed or do I need to change something in the pump itself?
Thanx in advance for the info.

What kind of pump do you have? Stock for Ford pumps are crap, you could swap on a bigger pulley but this would only help at very low rpm and would wear out the pump faster. Swap in a saginaw pump, you can modify these easily to produce more pressure, I beleive west texas offroad site has all you need to know about that.