larger tires, lower gears. stock tires 3.42, 35's with 3.73???

[alvincb3]

I’ll try to keep this short and sweet.

 

I have a 2014 Sierra 1500 4x4 (Crew Cab, SLT, Z71, blah, blah, blah) with 3:42 gears.

 

I’m running stock rubber. 275/55 R 20. I believe these are 31.9 inch tall tires.

 

My plan is to lift my truck and tune it as soon as I hit 36,000 miles. I want to run 35’s after I get my 6 inch lift installed.

 

I found this calculator. http://www.4lo.com/calc/geartire.php

I’ve been pretty obsessed with it and the numbers it’s giving me since I found it.

 

If I want to run a 35 inch tire, my current tire size is 31.9, and I have 3.42 gears front and rear, to keep the same gear ratios, I’d need a 3.75:1 axle ratio. Which is pretty close to 3.73. Catch my drift?

 

I know I’ll never get the acceleration and fuel economy back after taller and heavier tires, but shouldn’t my truck be pretty close in drivability and at least in the same ball park with stock fuel economy and acceleration if I were to install some 3.73 gears at the same time as I installed the tires?

 

Someone out there has to have done this same swap with this setup.

 

Just curious about the results.

 

[Rawyzf]

Higher gears is going in the wrong direction if you want to retain fuel economy.

 

These gears will be needed to get the truck moving though, as you suggested.

[alvincb3]

My thought would be that an engine not working as hard to move the vehicle around will get better mileage with in reason. I'm not, nor do I claim to be, an automotive engineer.

[LifeisthePits]

I am running 37's with 3.42's and get 16 mpg with a good tune and it gets up and goes like a beast still, hell I can still do some aggressive burnouts. These trucks are different from everything I have had in the past. I always did 4.88 gears with 37's for performance and would never have gone less than 4.56. With this powertrain set up I am just going to go with 4.10's, which is very unlike me.

 

In my opinion going from 3.42 to 3.73 is not worth the money unless you are going to be towing a lot but even than I would recommend going to factory 4.10's.

 

If you truck is going to be mainly a street queen I would throw on an intake, get a good tune that sets shift points and stick with the 3.42's with 35's, you will be surprised at the mileage and power.

[stevencox93]

Yeah I have 3.42's and 35s and really i suggest a good tune. Ive seen 20mpg with my 35s before but i hate to say it i don't get that now with my new tune because well.....I got addicted to the performance tune Lew gave me so Id prefer the speed and power now haha

[alvincb3]

I'm planning on going to with Black Bear when the time comes. Who is Lew? I'm pretty new here.

 

Yeah I have 3.42's and 35s and really i suggest a good tune. Ive seen 20mpg with my 35s before but i hate to say it i don't get that now with my new tune because well.....I got addicted to the performance tune Lew gave me so Id prefer the speed and power now haha

[LifeisthePits]

Yeah I have 3.42's and 35s and really i suggest a good tune. Ive seen 20mpg with my 35s before but i hate to say it i don't get that now with my new tune because well.....I got addicted to the performance tune Lew gave me so Id prefer the speed and power now haha

Same here, when I was running 35's I got 19 range but couldn't handle the tame tune. I am very happy with the 16 MPG on 37's with those low ass gears.

[Newm]

 

I'm planning on going to with Black Bear when the time comes. Who is Lew? I'm pretty new here.

 

 

http://www.diablewtune.com/

 

Just another tuning option.

[hemipowered22z]

I run 35s with a 3.42 and get @19 on the highway all I have is a SCT tuner and Lorado tonno. Truck has plenty of power. I do plan on going to 37s once a set of 4.10s or 4.56s are available from Yukon. My Father in law has a Hemi Ram with 33s and doesn't get as good of mileage as my truck does. The programmer really helped my trucks fuel economy.

[hemipowered22z]

I am running 37's with 3.42's and get 16 mpg with a good tune and it gets up and goes like a beast still, hell I can still do some aggressive burnouts. These trucks are different from everything I have had in the past. I always did 4.88 gears with 37's for performance and would never have gone less than 4.56. With this powertrain set up I am just going to go with 4.10's, which is very unlike me.

 

In my opinion going from 3.42 to 3.73 is not worth the money unless you are going to be towing a lot but even than I would recommend going to factory 4.10's.

 

If you truck is going to be mainly a street queen I would throw on an intake, get a good tune that sets shift points and stick with the 3.42's with 35's, you will be surprised at the mileage and power.

 

 

Don't mean to get off track (I did comment on the topic) but what are you running to clear your 37s? Im assuming a MCG 7-9?

[LifeisthePits]

 

 

Don't mean to get off track (I did comment on the topic) but what are you running to clear your 37s? Im assuming a MCG 7-9?

Yes sir, 7-9 SS Kit set at 9 with the AAL. I have 20x10 -24 Fuel's with 37x13.50 Mud Graps. I do rub in the back of the front fender at full lock with that set up. I will be going back to stock bumpers and adding a 3" body lift so I can run 20x12 -44 wheels without any rubbing issue at all.

[Danthaman69]

I would go with 4.10 gears but I'm waiting Yukon too. I get 14-16 mpg on the hwy. My truck needs gears its a pig. I'm use to going fast. I also tow with my truck 1-2 a mth but summer time its like 1-2 a week.

[hemipowered22z]

Yes sir, 7-9 SS Kit set at 9 with the AAL. I have 20x10 -24 Fuel's with 37x13.50 Mud Graps. I do rub in the back of the front fender at full lock with that set up. I will be going back to stock bumpers and adding a 3" body lift so I can run 20x12 -44 wheels without any rubbing issue at all.

Well I don't think my plan is going to work then. May have to come up with a new one. I was going to try to clear a 37x13.50 Nitto Trail with my RCX 7 and 1.5" Zone body lift but I don't know if that will work now. My wheels are 20x10 (-19). Maybe a 37x12.50 will clear but that tire might look to skinny.

I would go with 4.10 gears but I'm waiting Yukon too. I get 14-16 mpg on the hwy. My truck needs gears its a pig. I'm use to going fast. I also tow with my truck 1-2 a mth but summer time its like 1-2 a week.

 

I was told by a Yukon rep that it would be by the end of the year but we will see.

[Danthaman69]

Well I don't think my plan is going to work then. May have to come up with a new one. I was going to try to clear a 37x13.50 Nitto Trail with my RCX 7 and 1.5" Zone body lift but I don't know if that will work now. My wheels are 20x10 (-19). Maybe a 37x12.50 will clear but that tire might look to skinny.

 

I was told by a Yukon rep that it would be by the end of the year but we will see.

I read that today. Pretty disappointed. May end going with another company.

[hemipowered22z]

I read that today. Pretty disappointed. May end going with another company.

 

Yukon will probably be the 1st to release a ring and pinion specifically for our trucks. you can do a Frankenstein type rear end with parts from East Coast Gear but its very expensive due to having to buy parts that you wouldn't normally need with just a normal ring and pinion swap.