Original equipment manufacturer (OEM) or stock rims are factory wheels shipped with the vehicle from the car manufacturer. The materials and style options for stock wheels vary by the automaker. Stock rims range from painted steel with a decorative hubcap to oversized aluminum alloy wheels. Each type of stock wheel is designed to fit a specific vehicle and provide the rolling circumference required for the vehicle speedometer to display the correct speed. Factors including bolt pattern, bolt spacing, wheel width and wheel diameter determine the type of stock wheel that matches a particular vehicle make and model.
Bolt patterns for stock wheels vary from four-bolt—small passenger cars—to eight-bolt plus—large trucks—configurations. The spacing between the bolts is manufacturer-specific and the combination of number of bolts and bolt spacing will determine the correct OEM wheel for a specific vehicle. Wheel width and diameter are standard dimensions used to determine the tire size required to fit the rim. Using the OEM tire size on a stock rim ensures the vehicle speedometer displays the correct vehicle travel speed. Changing from one stock rim to another stock rim from the same vehicle manufacturer reduces the guesswork involved when ordering custom wheels to replace worn or unappealing stock rims.
Hubcaps are a common decorative covering for standard-grade stock rims. A locking ring located on the inside of the hubcap holds it tight to the outside of a stick rim. Unfortunately, hub caps often work loose when a vehicle hits a bump, pothole or other roadside debris. This causes it to come off the wheel and expose the inner painted steel portion of the stock rim. Replacing hubcap-style rims with custom wheels eliminates the chances of a hubcap flying free of a rim but increases the maintenance required to keep the wheels clean and in good condition.
Custom wheels replace painted steel with chrome-plated steel or polished aluminum. Both types of wheels provide a durable, decorative alternative to stock rims. Aluminum wheels offer less weight than a chrome-plated steel wheel but require a lot of maintenance to ensure the clear coating protecting the aluminum is not damaged by corrosive brake dust or road side debris. Chrome-plated wheels are easier to maintain than aluminum wheels but are prone to rust and pitting in areas that place salt on the roads in winter.