Questions for Artists: Larger Canvases?

If the problem for the wrinkles is because of a smaller frame, you can either purchase a premade canvas at Blicks (costs quite a bit for the large ones) or if the problem isn't the frame, (wrinkles in the canvas are set-in) I say you could try laying the canvas flat on the floor use water and wet the canvas then lay a flat surface to cover the canvas for a couple hours (not sure how well it works for canvas' though). Never tried ironing it either..