My 20 gal. (Home Depot) air compressor died today and I need to replace it to get my coach tires checked. I have been waiting, in the past, for the 20 gallon unit to get up to full pressure to air up 22.5 tires that were only 5#, or less, from being fully inflated. I am imagining I would be better served with a 3-6 gallon tank. I rarely use a impact wrench. What do you guys use?.