I find a lot of spares are way, way too fatty and I almost always trim bigger pieces of fat off before I cook. Also, if you remove the membrane there are lines of fat between the bones. Scrape those off with a spoon if they are too fatty.
The intramuscular fat is what really keeps your ribs moist, the outside fat doesn't do so as much. If you have a big hunk on there (usually it is on the bottom side where the smallest ribs are, the side away from the breastbone if you have a whole rack) cut it off.
LG BGE-Brinkman Cimmaron-Custom Pull-behind (old grade school boiler)-Weber Kettle-DCS 30"