No, it is not OK to replace just one tire. Your car or truck has four tires for a reason. They work together as a team to provide optimum performance, handling and safety. When one tire is out of commission, the other three have to work harder, which can lead to premature wear and tear on those tires. In addition, your vehicle will not handle as well with three good tires and one bad one. And if you happen to get into an accident, you could be found at fault because of your uneven tires. So do yourself (and your wallet) a favor – don’t replace just one tire.