The purpose of your Audi tie rod is to connect the motion you input on the steering wheel to the spindle on which the wheel of your car is mounted too. This is the last component of your vehicle that enables your car to turn. A majority of the tie rod ends used on Audi models are a simple straight bar that has a ball joint at the end with a stud protruding from it. This stud is the portion that is fastened to the spindle for a secure attachment. By requesting to your mechanic or technician for the old parts, you will be able to not only see what your tie rod looks like but also become aware if the person who changes your oil and greases your chassis is performing their job properly. There are a few of the Audi tie rods that are not fitted with a zerk or grease fitting. This is the part that permits grease to enter the ball joint. If yours is like that then the material in the ball joint is either Teflon or another long lasting substance that does not require the application of grease. Most owners of Audi's have a qualified technician replace their tie rods. If you do decide to do it yourself remember to count the rotations it take to remove the part from the shaft it is screwed into. This is important because this is the section of your steering that the adjustment to the toe on your car's alignment is made. Once you have replaced the tie rods on your Audi, it is further recommended to have the car aligned. This will help preserve the life span of your tires to their maximum and allow you to drive down the road with the steering wheel in the proper position.