kostyantyn_zhuk/Shutterstock Many repair shops will tell you that tie rods under your car can last somewhere between 50,000 and 100,000 miles. However, driving habits and road conditions ultimately dictate their lifespan. Although made of thin, high-strength cylindrical steel or cast iron, tie rods have ball joints that, while relatively durable, can prematurely fail due to potholes, poorly paved roads, and curb damage. The tie rod consists of two parts. The inner tie rod connects to the recirculating ball or rack-and-pinion steering via an inline ball joint on the inner end. Meanwhile, the outer tie rod connects to the inner rod on one end and to the steering knuckle on the other. It has a ball joint on the knuckle end, which has bearings and high-temperature grease inside, all wrapped neatly by a rubber boot. The assembly not only translates steering input to the front wheels, but the ball joints also allow the wheels to move up and down with the suspension, all while retaining steering control. And from that, it's not hard to see how things could go wrong. Jarring impacts from crater-sized potholes can bend the tie rods, but the ball joints are the weakest links. Considering the tie rods constantly move and flex as you drive or turn the wheel, the rubber boots can degrade and crack, allowing dirt and moisture to seep into the bearing housing. When that happens, the bearings undergo increased friction, which is when the three signs of bad tie rods begin to manifest. Steering issues Drazen_/Getty Images More friction means more wear, and this leads to unnecessary tie rod movements. As tie rods wear down, they negatively affect wheel control and make the steering feel loose or disconnected from the road. Worn ball joints on the tie rods are not as stiff as new ones, allowing for more side-to-side motion at the wheels. This can make the steering wheel shake or vibrate unnecessarily as you drive, particularly when speeding up or driving on uneven pavement. That looseness can also affect wheel alignment, which brings along a host of other problems. Of course, shaky steering and vibrations can also be due to unbalanced front wheels, which is among the primary warning signs that your car is due for wheel balancing. But if the annoying shakes are accompanied by a wandering feeling on the steering wheel or pulling to either side, you're most likely dealing with failing or overly loose tie rods. Inconsistent tire wear Yevhen Smyk/Getty Images Uneven tire wear can be caused by many things. For instance, consistently overinflating them can cause the center part of the treads to wear out quicker, while habitual underinflation can bald the inner and outer shoulders prematurely. Not enough air in the tire also allows the tire to flex too much, resulting in overheating. If that sounds like bad news, it is, since an overheating tire will affect its rolling resistance and result in poor gas mileage. Remember the part about failing tie rods having loose ball joints? That looseness also affects the wheel alignment, and it can cause the front tires to wear unevenly or display symptoms of cupping or feathering. Moreover, tires with uneven treads produce more road noise and can affect the handling and performance of your car. If you notice one or two front tires wearing faster on the inside or outer edges, have the tie rods checked immediately before the tires get so unevenly worn that replacing them becomes mandatory. Knocking, clunking, and grinding noises Gumbariya/Shutterstock Are you hearing unusual and varying knocking or clunking noises from the front of the car when turning the steering wheel, specifically when parking or maneuvering at low speeds? Similar noises can come from worn shock absorbers, bad struts, control arms, or damaged constant velocity (CV) joints, which can also cause issues with the transmission. However, they are also a common symptom of bad tie rods – especially when going over bumps or turning the wheel. Meanwhile, ball joint bearings that are contaminated with dirt and sand can cause grinding noises as you move the steering wheel. Despite the symptoms, the only way to tell if it's time to replace the tie rods is to do a thorough, visual inspection. That means bringing the car to a mechanic or — if you're mechanically inclined – raising the front end, wiggling the front wheels for excessive play, or removing the wheel and the tie rods to inspect the rubber boots and ball joints. How much to replace the tie rods? Andrewshots/Shutterstock The cost of replacing your car's tie rods will depend on its make and model. However, you can expect to pay between $100 and $400 for parts and up to $100 or more for labor. It's best to replace tie rods in pairs. For instance, if the left outer tie rod has gone bad, replacing the right outer tie rod with it is a good idea, since both have succumbed to the same degree of wear and tear. Also consider replacing the inner and outer tie rods at the same time, especially if you have a high-mileage car, a performance vehicle, or if the inner tie rod is already exhibiting signs of wear. Lastly, it's highly recommended to get an alignment after replacing the tie rods, particularly the outer tie rods that are critical to the toe-in and toe-out adjustment of the front wheels. Changing the outer tie rod will mess with the factory toe angle, and misaligned front wheels will cause excessive tire wear and poor handling.