Hello all, 89' F-150 302 5spd 4x4. . . with a 3.08 rearend, checked by counting driveshaft revolutions. But the tach says at 55mph in 5th gear, I'm turning 2050 rpm. That can't be right. its supposed to be around 1600rpms. Are these tachs not accurate? can a sensor be wrong? What do you all think? FYI, speedo is INOP.
Thanks
Timmy

 

The tach is pretty accurate on mine. What size tires are you running? How do you know you're going 55?

 

I am running I believe stock tires. . . 29 inches. But the tire says 31*10.5. But it measures 29 tall. I know I'm running 55 because I have had multiple cars confirm it, andmy dads GPS. So I am sure of that. But something just isn't right. So. . . . I gotta figure it out.
Thanks,
Tim