I had 4.56's with 34s and it was geared just about perfect for the highway.
You gotta remember, especially if you're talking about going 80 MPH, you're moving around a LOT of heavy rubber with a 37" tire.
From a pure math standpoint: With a 37" tire, 55 MPH, OD Off / On, you'd be at:
3.55s 1769 / 1185
3.90s 1944 / 1302
4.10s 2043 / 1369
4.56s 2272 / 1523
4.88s 2432 / 1629
Now at 80 MPH
3.55s 2573 / 1724
3.90s 2827 / 1894
4.10s 2972 / 1991
4.56s 3305 / 2215
4.88s 3537 / 2370
Two big things to think of:
1: 37" tires are not highway tires. Period.
2: Don't fear the gear! Around town and on the highway, having the RPM's up higher with massive heavy tires will be to your advantage. Think about trying to pass someone, lay into it, and you truck just bogs. Very unsafe.
