I had 235/60/15s on my Cobra if I remember correctly and a 3:27 rear end ratio, with the .68 split in the transmission. I checked it with the highway patrol radar and the readings were right on. 70 MPH in 5th was 1900 RPM and 60 MPH I don't remember, but the engine was more of a racing engine and I didn't even use 5th on the freeway about 70% of the time as the traffic caused the engine to lug. But 2nd, 3rd, and 4th worked very well. However if I had another car I think I would go to 3:56 gears and a much milder engine.
Ron
