* Gear Ratio: Different Chevrolet models, and even different trims of the same model, have different gear ratios in their transmissions (automatic or manual).
* Tire Size: Larger diameter tires will result in lower RPMs at the same speed compared to smaller tires.
* Transmission Type: Automatic transmissions will generally have slightly lower RPMs than manual transmissions at the same speed.
To find the approximate RPM for *your* specific Chevrolet at 55 mph, you'd need to consult your owner's manual or use an online RPM calculator (many are available with a quick search) that allows you to input your vehicle's specifications (year, model, engine, transmission, tire size).
