Pinion bearings are a vital part of any vehicle's suspension system, and they play an important role in keeping your car driving smoothly. Generally speaking, pinion bearings can last anywhere from 50,000 to 70,000 miles before needing to be replaced. However, this number is highly contingent on the condition of the bearing itself as well as how it was maintained over its lifetime. If you don't regularly replace worn-out parts in your suspension system or perform routine maintenance on these components, then it's likely that your pinion bearings will need to be changed much sooner than normal. Additionally, if you drive off-road or tend to use your vehicle under extreme conditions (like during racing), then you should expect that their lifespan will decrease significantly due to increased wear and tear. So while there is no hard rule for exactly how long a pinion bearing can last for each individual vehicle—it ultimately depends on a variety of factors—you should always keep an eye on them and make sure they're properly lubricated in order to get the most out of them!