Drive line question

[Guest Lenny]

Lenny, unless you are doing something i am not reading about, is not the drive line going to spin the same as engine rpm which i know you are not going to keep under 1800, you do not drive like grandma.

Here Is the way I'm looking at it. I'm running 31" (8.115 feet circumference) tires and at 75 MPH (6600 ft/min) they turn at 813 RPMs. The differential has, If I remember correctly, a 2.13:1 radio. That means the driveshaft is spinning at 1732 RPMs. But now you have me wondering if I'm missing something. A typical car transmission in high gear has a 1:1 ratio or even less in overdrive. which means the driveshaft runs at the same or faster then the engine. What is the average car tire, say 24" diameter or 6.28 feet around? If a car will do 120 MPH then the wheels are spinning at 1681 RPMs. If the typical car differential is say 3.5:1 then the driveshaft would be at 5885 RPMs. So then the engine would, with a 1:1 tranmission ratio, be turning at 5885. This sounds about right as the engine isn't going to be turning at it's max RPMs when pushing the car at 120 MPH. The Trooper must be geared down in the trans even in 5th gear. That had me nervous for a minute but seems I'm going to be OK. Thanks again flatbed, I'll have to stay on my toes with you watching and I do appreciate your guidance.

Lenny