Engine RPM at speed calculator

[Rickf1985]

Here is a calculator to figure your rpm at whatever speed you are driving. Probably not perfect but close enough.

http://spicerparts.com/calculators/engine-rpm-calculator

[87Itasca]

If I remember right, most P30 units had a 4.56 rear gear. If so, then mine is turning about 2500-2600 at 55 MPH. A bit surprised, as it just seems (sounds) higher than that.

[Rickf1985]

Neat little tool isn't it?