* Bolt Pattern: Check the bolt pattern for both the 1999 Mustang rims and your Ranger. They need to be identical. A common bolt pattern for Mustangs is 5x4.75" (5 lug nuts on a 4.75" circle), but there might be variations depending on the model and year of the Mustang. Rangers also have several potential bolt patterns depending on the year and model.
* Hub Bore: The center hole of the rim (hub bore) must be the correct size to fit snugly over the Ranger's wheel hub. If it's too small, it won't fit; if it's too large, it will wobble dangerously.
* Backspacing/Offset: This is the distance from the wheel mounting surface to the back of the rim. The wrong backspacing can cause the tire to rub against the suspension or body of the truck.
In short: You MUST check the specifications (bolt pattern, hub bore, and backspacing) of both the 1999 Mustang rims and your Ranger's wheels to be sure they are compatible. If even one doesn't match, the rims will not fit safely. Look up these specs online using the year, make, model, and trim level for both the Mustang and Ranger.
