I am ready to put new gears in my truck and am not sure what gear ratio to use. I have 35 inch tires with a six inch lift and of course a 4.9 straight six with the p.o.s. 5 speed tranny. The gear shop says I should go to 4.56 and others say 4.10s. I drive on the freeway a lot but also drive in the mountains and off road. Does any one have either of these combinations? I like to keep as much power as possible. The reason I ask on this board is because the six has a different power band than the v8s. Any advice is appreciated.

 

Well i have 4.30 gears in my 2000 mustang Gt and it killed the gas milage but the 1/4 is great.

But with your tall tires it reduced the actual gear ratio, either way should be fine the 4.56 will loss some MPG on the highway but would be a hell of a lot better off road. Like me you have to decide what is important to you I drive my car about 1k a year so MPG is not so important to me. If your truck is your daily driver the 2 bucks a gal gas price might dictate the 4.11 gears.

 

With 35" tires 4.56 will take you just about right back to stock, maybe just a little lower, but that's good for the power band of your straight 6. The rule of thumb is 1/10th of increased ratio for every inch in tire height over stock to retain your stock performance. The gear shop was right; you'll be happier with the 4.56. 4.10 will give you slightly better milage, but you'll notice that you still don't have as much power as you think you should, and 5th gear will still suck.

In my "other" wheeler, I have a 4.0 straight 6 with 35's and 4.88 gears, and it is literally a hot rod (I have some power goodies, too, though). I have very little top end, though. 80 is about as fast as I can comfortably go. I had 32's with 3.73 and it was a dog. A buddy has 4.56 with 35's, and his vehicle drives very nice. Good power, good on road manners.

 

Thanks for the reply. I just worry I will be maxing out the motor at 70mph on the freeway. why will 5th gear still suck? On I-5 most people are going 80 and will get run off the road at 70.

 

5th will suck because of a lack of power, especially when pulling up long grades. Even slight grades will show a definite lack of power. It's all about putting your engine back into it's power band for a given speed. If you tow, 5th will become virtually worthless with the wrong gear/tire combo.