* Bolt Pattern: This is the most critical aspect. You need to determine the exact bolt pattern of your 1979 F-250's 16.5" wheels (likely 8x6.5" but double-check). Then, find the bolt pattern of any potential replacement wheels. They *must* match.
* Wheel Backspacing: The distance between the mounting surface of the wheel and the hub is called backspacing. Incorrect backspacing can cause clearance issues with the brakes, suspension, or body. Wheels from the same year and model *should* have compatible backspacing, but it's not guaranteed, especially if different axle options were available.
* Hub Diameter: While less common to be a problem with Ford trucks of this era, make sure the center bore of the replacement wheel is large enough to fit over your truck's wheel hubs.
* Wheel Size and Tire Size: Switching from 16.5" to 16" requires new tires, and you'll need to consider the overall diameter of the new tire and wheel combination to ensure it doesn't affect your speedometer accuracy or cause rubbing issues. The overall diameter should remain relatively close to the original.
In short: While wheels from similar years are more likely to fit, you MUST verify the bolt pattern and backspacing before purchasing any used wheels. Using a reliable parts website and specifying your truck's details (VIN is best) can help you find exact compatibility. You can also look at the wheels themselves; the specifications (bolt pattern, diameter, backspacing) are often stamped on the back.
