my RPM's at 60 MPH

[dukcaln]

So got that tach in the truck today and went down the road.. Seems I a seeing 3000 RPM at 60 MPH. I am running 255-60-15 rear tires (almost new). The speedo may be a tad off so will verify with the GPS tomorrow because it started raining.

I also need to verify the rear end ratio. I thought I had 3:73 gears, at least that is what we figured out when we measured a full rotation.

What do you all think.... anybody figure out my rear end ratio by RPM and Tire Size vs speed. If the speedo is off it is by only a couple MPH...