Ring-and-pinion size is important when considering axle strength. Lower ratios mean fewer teeth on the pinion gear; this in turn makes for a weaker gearset. So bigger is better here. From left to right is the Dana 60 gearset found in our Pro-Rock axles, a Dana 44 set, and the dinky Dana 30 parts. It really depends on the weight of your rig and your driving style, but the 60 gears are good for tires up to 48 inches, the Dana 44 cogs are good for up to 35s, and the Dana 30 gears shouldn't be pushed by more than 33s.