The overall ratings of three Auto Parts stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Tower International (NYSE:TOWR) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Tower International is a global manufacturer of engineered structural metal components and assemblies, primarily serving automotive original equipment manufacturers. In Portfolio Grader’s specific subcategories of Earnings Momentum and Cash Flow, TOWR also gets F’s. The stock price has dropped 5% over the past month, worse than the 1% increase the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of TOWR stock.

This week, China Automotive Systems (NASDAQ:CAAS) falls to a D (“sell”), worse than last week’s grade of C (“hold”). China Automotive System designs, markets, and sells custom-designed stained glass and leaded glass artifacts.

For a full analysis of CAAS stock, visit Portfolio Grader.

This week, China Zenix Auto International (NYSE:ZX) drops from a C to a D rating. China Zenix Auto International designs, manufactures and sells high quality steel wheels that are widely used by most types of commercial vehicles. To get an in-depth look at ZX, get Portfolio Grader’s complete analysis of ZX stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.