Big Tires, Bad Gearing... gear ratio issue?
 

Just purchased a 2008 H3 Alpha. The guy who had it before me put a 4" Tuff Country lift on it and 37" tires (also a straight exhaust... or rather, no exhaust).

It sounds great, it looks mean, but something doesn't seem right.

At highway speeds the H3 wants to drop down a gear even on very gradual inclines, or sometimes no incline. Oh, and my gas mileage is pathetic (I realize that this is a product of extremely heavy tires and no exhaust -- and it's an H3 -- but I'm talking like 8 or 9 miles to the gallon here).

Do I need to change my gear ratio in order to fix this problem? Rumor is this is a necessary step that I don't think the previous owner did.
What's the easiest way to tackle this?

The gears would help and also getting a tune done. You very well migh want to really look at the exhaust and get a muffle out back on... Did he eliminate a CAT? Also what about an intake?

I think if you can actually find the gears required,AND the cost,you will do the sensible practical thing,buy a set of 285 +- tires.
It wont be realistic to do a gear swap.

I highly recommend replacing the exhaust with something. Oftentimes having no backpressure as a result of no exhaust will cause a modern computer driven engine to run like crap, have loss of power, and get horrible mpg's.

Also, if this is going to be a daily driver, going to 35's would save you much money on fuel and your brakes and suspension components will last much longer. And it'll still look great with the lift.

...Oh yeah, welcome to the forum and post up some pictures of that beast!

Either 35's or find a way to get up to 5.13's or 5.38's

Here is what you need to know, all H3s essentially have the same axles (alphas and 09/10 adventures have a cast iron front diff instead of aluminum), AAM 10 bolt w/ 8.5" ring gears.

Alphas come with 4:10 gears, I5s come with 4:56 gears. The lowest ratio that will fit in an AAM 10 bolt is the 4:56.

So, in the gearing department your ONLY stock axle option is to swap your Alpha 4:10s with I5 4:56s.

1/3 solution/s
 

Yeah the 37s are going to be around for a while. They're 12 wide with negative offset and look retarded mean.... and more importantly no one else has them.

Alright, so if gear ratio change isn't realistic then my only option is the exhaust. I probably am missing back pressure causing the engine to run sub peak. I think - or hope rather - that a tune will help out and/or reveal that I need exhaust.

I hope thats the largest cause of the issue, I mean an extra couple inches on the wheels can't be the most significant reason for the truck to always be right on the edge of dropping to 3rd at 70 mph. Honestly i dont give a **** about the gas mileage but the constant gear change should not be happening on the V8.

SO... what's the word seasoned H3 owners? Give me the bottom line on best exhaust (its gotta have that awesome loud low grumble I've got now.... the guy whole sold it to me said he had already tried flow master and magnaflow, and they were just too quiet -- also it'd be nice if the suggested exhaust doesn't trip my check engine light).
AND... what's the best super chip? HollaBack.

I'm running Flowmaster on my T and I want louder, always thought shorter tial pipe would make it louder but it didn't. I was told to ditch the second cat and put a cherry boom in it place (02 sensor is right after the header) it it'll help. I know there a programer for the 5.3 but everyone and myself runs the PCMforless rout.

Hollered back at ya via email :P