My brother in law wants to put gears in his truck. 2010 silverado 5.3 6l80e 4 door z71. It has long tubes and black bear tune on it now with 3.42 gears. He was thinking he wants 4.30 gears. Does anyone else have this combo? I've seen many people on here with 4.10s with a 6 speed and they like them. He doesn't want it to kill gas mileage on the highway but he is looking for more low end power and plans to eventually tow a travel trailer. What is y'all's opinion? Stock wheels and tires on it also. He might get a little bigger tire when these wear out but only up to a 33inch tire.

 

Anyone?

 

My 4.11s are great, wouldn't change a thing. If he wants 4.30 then go ahead. It *might* be a tad too much gear but he won't hate them I know that. During my decision I didn't want to go much more than 2500RPM while cruising at 80mph on interstate. I really don't think the engine cares about purring at 2500 for a long cruise but for me I didn't want that. So my suggestion is to look at the RPM he's comfortable with turning at his favorite highway speed. Hell, 01WS6/tamu went 4.56 in his stock drivetrain 6.2 and stock 20s and he loves it. I've also found out that my RPM doesn't really matter for MPG, I get the same as when I had 3.08s. 75+mph my MPG goes down, below 72ish I can get decent, depending on wind direction.

 

Also, do they make 4.30 gears for 4WD? I thought it jumped from 4.11 to 4.56. I am assuming Z71 means its 4WD...

 

Yes it's 4x4. I haven't looked for the gears yet. He just told me 4.30. If they don't make a 4.30 we will go with 4.11. I think 4.56 would be too much.

 

4.30 is a good gear but I don't think its available for the front 8.25IFS differential.

 

I don't think they make 4.30s for the front, can't remember, but when I had 4.56s with the stock tire it was way too much for the hwy, IMO. For the city its fine though. I got better mileage city/hwy with 4.56s and 33s then with 3.42s and stock tire size(275/55/20).

 

What is the factory tire height for the z71s with 18 inch rims?

 

31.5" tire spec but I believe that GM calibration is for 31.02"... 31" will get you close enough

 

I have 2010 LTZ CC truck 5.3 6spd blackbear tune with 4.11 and 32.6 tires tow an enclosed car trailer loaded 7000lbs base your rear gear on the hwy speed/ rpm you want BASED on towing in 5th gearif he going to tow a bigger trailer ...you wont be in 6th much I tow @ 2500 rpm in 5th @70mph

If he wants to tow in 6th then will need 4.56 at least but non towing hwy mileage will drop if he cruises over 2k non towing