Lifting and ReGearing

jmdll0518 · January 13, 2016

hi everyone,

New to this site. I just recently purchased a new 2016 Silverado 2500HD with the Duramax diesel. This is my second Silverado as my first was a 2004 Silverado 1500 LS.

I am looking at doing some modifications and one of them would be a suspension lift. I will be pulling trailers and the gearing is important. I would like to know if I added 35 in tires and a 6-7 inch lift, would I need to Re-Gear the vehicle for day to day driving and towing? Many thanks in advance.

SMiller · January 15, 2016

hi everyone,

New to this site. I just recently purchased a new 2016 Silverado 2500HD with the Duramax diesel. This is my second Silverado as my first was a 2004 Silverado 1500 LS.

I am looking at doing some modifications and one of them would be a suspension lift. I will be pulling trailers and the gearing is important. I would like to know if I added 35 in tires and a 6-7 inch lift, would I need to Re-Gear the vehicle for day to day driving and towing? Many thanks in advance.

Don't hate me for breaking the news to you but no one adds only 35in. tires on that big lift anymore, on these new trucks it would look like you have donuts installed.

I think you will find a Rancho 4in. lift (5.5in. actual lift) would be the tallest lift you would want for 35's.

Personally I think a leveling kit looks good with 35's or even a Cognito 4in. lift turned down and a 1in. block which gives you perfect angles on the suspension.

To get back to your question I drove my bosses truck (6in. lift 35's) today after driving my twin (stock size tires) for the last 3 days and I could tell a huge difference, it was as if I was taking off in second gear every time I took off and on the highway it was simply lazy and required a downshift to move vs my truck that just responds and goes.

IF I were installing a lift and big tires I would regear, not only would I regear but I would regear one size "bigger" to give myself more rpm to help move the extra weight and push the extra air. You will find the added rpm will actually get better mileage as the motor isn't lugging.

Sorry for the long post, anytime you go 35's or more I would regear, you will love some 4.88's with 35's, it will rip from a start and have the rpm in 6th gear to pull right along even loaded/pulling.

jmdll0518 · January 16, 2016

Thank you for the post. I was actually talking with an installer who recommended a leveling kit with taller tires. In the case I decide to go with the 35's I will see if he can also do the regearing of the vehicle. Honestly I paid $$$ for an extended warranty and I really don't want to void it. So maybe leveling it with the correct size tire is the way to go. Thanks again SMiller.

SMiller · January 16, 2016

Don't dismiss the Cognito 4in. left and 35's as it is a sharp look.

Duramax forum and diesel place have hundreds of pages of both leveled and lifted trucks, look through there, you will find the look you are after.

For me a leveling kit and 275/65/20's on stock wheels is the look I am going for, IF I was going 35's on aftermarket wheels I would do the 4in. lift with 1in. blocks in the rear and leave the gears as is but tune it to so it will fuel hard on take off so it doesn't feel so dead.

rocnrol · January 16, 2016

Great advice by SMiller, I also wondered about a regear after my recent tire change. Like many here, I went with some 295/70-18 and just leveled the truck with the stock keys. I have 4.10:1 ratio and using one of the many available ratio calculator on the interwebs, I'm now at a 3.90:1 effective ratio. To me it doesn't seem to be all that different, it's shifting one gear on the hills now on the way to work instead of not shifting before.

I haven't towed with it yet, but I don't think it will be much worse than stock.

CAtaylor · January 17, 2016

IMO. With the 6.6 I wouldn't even worry about the 35's and towing. I would worry much more about how much weight you will be towing with the lift.

Johnny26 · January 23, 2016

I purchased a 2015 3500 with the 6.6. I put a Cognito 7-9 lift on it, with 20x9 and 37s, that setup is perfect for these trucks. I have not re-geared "yet". I have only towed about 2k trailer weight so far and it was fine. I am not pulling all the time. The truck did fine I didn't have any issues and I didn't feel like it was a dog.

I am planning to get a big boat in the coming months likely to weigh around 4-5k including trailer and crap. I will most likely re gear at that point.

Buddy of mine has a toy hauler that he loads up on his 6.6, he has a 12 inch lift with 38s,stock gears and his truck does just fine.

Up to you really if you choose to re gear or not. If I were towing my buddies toy hauler I would re gear for sure.

Bit of advice, if you put a lift on do yourself a favor and get a Cognito lift. Its not cheap but then again you get what you pay for. Also, get the idler and pitman arm replacement kit as well. If you re-gear get a good set of gears, don't go cheap.

As far as warranty is concerned, the stock suspension is garbage to begin with so you are doing yourself a favor. With past lifted trucks, I have had issues where I took the truck in and they were fixed, no problem.