[Cowens]

I'm going to put 4.11 in the front and rear of my 97'4x4. It is an automatic with overdrive. I have 33 inch tires and I wonder how high would the RPM's be at 80 mph....and how bad is it on the tranny and on my truck to run at those speeds? And also if I put a Detroit locker in the rear would it drive on the pavement a lot different.

 

[WMIF]

Ive got 4.10's with 33's and my tach says about 3000 rpm at 100 mph. mines a V10 but it should be about the same.

 

[TUNIS]

I have 3.91 gears from the factory and I run 35" MT/R's and at 70mph, my tach is at 2000rpm...

 

[Bill_L]

I still have the factory 4.10s and 32 inch tires that came on my Off Road and freeway speed isnt bad.
somewhere around or under 2500 at 75. I don't really remember but it wasn't bad.
Faster isn't a problem either.

 

[does it matter]

i have a 318 auto with 4:10s and 36" tsl radials, turning about 2k @65mph

 

[unclemark369]

WEll I've got the 360 with auto trans, 285/75/16's might as well say 33's and 4.56 gears and I turn ruffly 2200 rpm's on flat ground with cruise control on running 70 mph. If your going to change gears you might as well go for the gusto and get the 4.56's that way you dont get disappointed when you get bigger tires. But if you want top end and you dont want larger that 33's than get the 4.10. If I did my math correctly to return to stock power and spec's you need 4.10's for 33's and 4.56's for 35 or 36's.