Pre 2000 D.O.T. date code will have 3 digits. First 2 are the week of production, the last number is the year. Example 228 22nd week of either 78, 88 or 98.
They may look good on the outside, but don't be fooled. Tires are made of several different chemicals that are baked in a mold under high heat and pressure to cause a chemical reaction called " Vulcanization" This is what made Mr. Goodyear famous, even though he was in jail when he accidentally found this out. Just like mixing eggs, flour, sugar, butter. Baking it and it turns into cake. Once it is made, it starts to chemically deteriorate. Tires were only designed to last 4-5 years at most. Old tires wore out quickly and were replaced every couple of years. Average mileage driven annually today is about 15K a year. A 60,000 mile tire would last 4 years. Take Motorhome and boat trailer, camping trailer tires for example. They see very few miles each year and because the rubber hardens and loses it flexibility it gets very hot at highway speeds and then disintegrates. That is what you see all over the freeways in the summer time. Old tires that fail. At the very least a failure will cause damage to your cars' fenders and more. At the worst you can cause a traffic accident and someone can be injured or worse.
No LOL here. I learned this information from over 35 years in the tire business with major tire manufacturers. Been involved in a few major tire recalls. No fun.