Keep an eye on the tire sidewalls. If there is cracking or crazing visible on the sidewall, it is time for new tires. Those are called "gum wall" or "skinwall" tires referring to the natural rubber strip making up the sidewall. They start out lighter in color than what I see on your bike and that is a sign of aging. I didn't know they still made them but Niagara Cycle where I do a lot of my online bike parts ordering has several in the old 27" X 1+1/4" or 27" X 1+1/8" size common on 70s and 80s road bikes. You can see the original color here: Kenda K35 27 x 1-1/4 Skinwall Tire