* Gear Ratio: The ratio of engine speed to driveshaft speed. Different transmission gear ratios (manual or automatic) and rear axle gear ratios will significantly affect RPM. A higher numerical gear ratio will result in higher RPM at the same speed.
* Tire Size: Larger diameter tires will result in lower RPM at a given speed compared to smaller tires. If you've changed tire size from the factory specification, this will affect RPM.
* Transmission Type: Automatic transmissions shift differently than manuals, affecting the RPM. Even within automatic transmissions, different shift points (programmed or adapted) can vary.
To find the approximate RPM, you'd need to know the specific gear ratio (both transmission and rear axle) and the tire size of your *particular* 2007 Dodge Ram. Then, you could use an online RPM calculator (easily searchable online) to estimate it.
Without that information, any answer would be a pure guess and potentially inaccurate.
