Time yourself over a measured mile at a relatively steady speed. 60 seconds for one mile = 60 MPH. For other speeds a little simple math will get the job done. For instance- - - - -a 50-second mile would compute as follows: 60 divided by 50 = 1.2 miles per minute. 1.2 X 60 = 72 MPH. A 70-second mile = .85 miles/minute, or 51 MPH.
70 MPH, unless you've got the extremely scarce 4.11 ratio rear end gears, would be a stretch with a 1-ton with normal-height tires. My 59 model 3800 dually with 18" wheels had a hard time maintaining 65 MPH for very long.
Jerry
