38's are a pretty tall order but I do have 38's on my 1983 Miyata Six Ten. It came with 27" wheels but 700c fit with only a canti brake adjustment. I didn't set the frame. The rear required me to manually spread the dropouts but I have removed and replaced the wheel several times and though a slight pain ,not at all insurmountable. My Trek 400 with USA True Temper double butted frame will fit 35mm tires but I would be more comfortable running 32's if mud was involved.