I think I heard that stainless steel is also self lubricating, not very good in an application with a lot of vibration.

The wheel bolts and I would think studs will be made of hardened steel. Different to zinc coated or plain mild steel bolts and much stronger in tension.

Marine grade stainless bolts have a higher shear point i believe, better than that of EN8 which is a high carbon steel, 318 grade

Jordan