When choosing between aluminum and stainless steel running boards, you have to ask yourself what your practical needs for your Toyota Tundra are. This is because stainless steel running boards are more robust than their aluminum counterparts and can therefore be used in more severe conditions.  Stainless steel can support more weight than aluminum, making the steel running boards more suitable for those Toyota Tundras used in agriculture, off-road, etc.  Damp conditions should influence your choice, as you will need running boards that are more corrosion-resistant. Marine-grade aluminum is more corrosion-resistant than other types of aluminum, while stainless steel is corrosion-resistant because it contains chromium. Therefore, if you want lightweight running boards that are corrosion-resistant, you need to ensure that the boards are made from a marine-grade aluminum alloy. Otherwise, stainless steel running boards will do the job.