Tire Trade-in Value

I usually trade in my tires at around 50,000 miles, which, using our normal travels, amounts to every 3-4 years. My trade in has varied between $100-150 per tire. My tires have not aged out and they certainly are not worn out but I prefer the ride and reliability of newer tires. There is nothing obviously wrong with my trade-in tires but neither I nor anyone else can tell what will happen in the next 10 miles. The dealer that gives me the trade in value for my tires will sell those tires to someone at a price that the buyer is happy with and they may provide safe service for another 50,000 miles or they may fail as he drives down the road tomorrow. The dealer can't tell for sure and I don't care since they are not my tires any longer. If you have read this forum very often, you will hear about owners that have had blowouts with fairly new tires. You will also read about people that have used tires for 12 years without a problem. The facts are that no one can say when a tire will fail, whether you own it or the next buyer owns it.