I have 27's and did not notice a power loss. I added a lift and lift springs at the same time, and did not notice a power difference, only a handling difference. My bike is 2wd and with the Mud Lite XL's I can go places I never could have before. Look at the pictures in my gallery. I was considering the swamp lites but when I saw them in person I was disappointed. They look more like an all-terrain tire than a mud tire.