Choice of rear axle ratio would you pick?

rocc · December 7, 2013

I got the 2013 (yah, I like rebates) and in 5.3l 3.42 just got 20.7 mpg on 410 miles (425 total on engine, first 15 before they filled it for me) on 19.8 gallons. And that is without your 2014 ecotech engines, which if you drove as slow as I do, you should get a couple mpg's better than me. This is bare stock ECLB tow kit, tint, electric door locks (which I have more difficulty changing than windows, but oh well). If anything may add K&N drop-in + MIT air tube later.

That is about 70% freeway, 20% 35-45mpg roads some traffic with lights every 1/4 to 1/2 mile, and 10% pure city type driving with couple times rush hour 'just barely moving.' Seems to be getting smoother & smoother on shifts & where chooses the rpms. Checked the oil, feeling just bit gritty so will change for break-in doing dexos- thing (thanks Walmart). Pretty good- up 4 mile hill Freeway(steepest grade 45) kept good torque, no-need downshift.

Scout_ · January 7, 2014

Hello, First time poster, first off I want to apologize for resurrecting a dead thread but after reading the entire thread I feel this would be a pretty good place to ask my question.

Ok, I have a 2014 Silverado LT Z71 with a 3.08 axle. I am wanting to add some 33'' tires to the OEM 18'' rims but, I really like the look of a polished 20'' rim with the model tires I've picked out. Now I know that with the axle ratio I have it will change things with just putting bigger tires on, and it turn into a bit of a dog, nevermind changing the rim size.

So basically my question is it a good idea to change the rim size to 20'' and add 33'' tires to a 3.08 axle?

As for towing and usage, the most I would be towing/hauling for the foreseeable future is a 500 lb ATV in the bed or 2 ATV's of the same weight on a 2000lb single axle utility trailer, and a 18' boat. I live in South Louisiana so not much hill climbing will I be doing. Other than that its a daily driver highway truck, mudding isn't for me, that's what I have a ATV for.

Again, sorry for bringing up a little bit of a heated thread, I'm not looking to start the 3.08 vs. 3.42 debate going again, just seeking advice and information.

Thanks, Scout

crushNchowda · January 7, 2014

Hello, First time poster, first off I want to apologize for resurrecting a dead thread but after reading the entire thread I feel this would be a pretty good place to ask my question.

Ok, I have a 2014 Silverado LT Z71 with a 3.08 axle. I am wanting to add some 33'' tires to the OEM 18'' rims but, I really like the look of a polished 20'' rim with the model tires I've picked out. Now I know that with the axle ratio I have it will change things with just putting bigger tires on, and it turn into a bit of a dog, nevermind changing the rim size.

So basically my question is it a good idea to change the rim size to 20'' and add 33'' tires to a 3.08 axle?

As for towing and usage, the most I would be towing/hauling for the foreseeable future is a 500 lb ATV in the bed or 2 ATV's of the same weight on a 2000lb single axle utility trailer, and a 18' boat. I live in South Louisiana so not much hill climbing will I be doing. Other than that its a daily driver highway truck, mudding isn't for me, that's what I have a ATV for.

Again, sorry for bringing up a little bit of a heated thread, I'm not looking to start the 3.08 vs. 3.42 debate going again, just seeking advice and information.

Thanks, Scout

You know it's a bad idea or you wouldn't be asking. The truck isn't a speedster to begin with (355hp) and w/ the 3.08 you're already suffering in the torque dept. if you're going to do it no matter what I'd look at the both the cost of getting into at least a 5.3 3.42 or a max trailering 3.73 or better yet. 6.2 w/ 3.42 vs. the cost of swapping gears out on your current truck BEFORE you go buying tires and rims and lifting it.

KMGZ400 · January 7, 2014

Hello, First time poster, first off I want to apologize for resurrecting a dead thread but after reading the entire thread I feel this would be a pretty good place to ask my question.

Ok, I have a 2014 Silverado LT Z71 with a 3.08 axle. I am wanting to add some 33'' tires to the OEM 18'' rims but, I really like the look of a polished 20'' rim with the model tires I've picked out. Now I know that with the axle ratio I have it will change things with just putting bigger tires on, and it turn into a bit of a dog, nevermind changing the rim size.

So basically my question is it a good idea to change the rim size to 20'' and add 33'' tires to a 3.08 axle?

As for towing and usage, the most I would be towing/hauling for the foreseeable future is a 500 lb ATV in the bed or 2 ATV's of the same weight on a 2000lb single axle utility trailer, and a 18' boat. I live in South Louisiana so not much hill climbing will I be doing. Other than that its a daily driver highway truck, mudding isn't for me, that's what I have a ATV for.

Again, sorry for bringing up a little bit of a heated thread, I'm not looking to start the 3.08 vs. 3.42 debate going again, just seeking advice and information.

Thanks, Scout

I wouldn't be afraid to go to 20's and 285's with a 3.08 truck, it may have a slight impact but it won't be as drastic as some will say. Any bigger then 285 might be pushing it

Dj0nes · January 7, 2014

3.42's here with no regrets. Could only imagine the 3.73's tho! Have them in my Cummims and love it.

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divicevich · January 7, 2014

Have the 5.3 4x4, 20" rims with the 3.08. Changed stock tires to a terra grappler 285 which is a 33" tire but actually measures 32 1/4" on truck. No problems at all, just purchased the hyper tech speedo calibrator to keep the DIC accurate.

Scout_ · January 7, 2014

Thanks for the reply's guys, I'm still going back and forth on whether to get 33's on 18' or go with 20 inch rims.

Have the 5.3 4x4, 20" rims with the 3.08. Changed stock tires to a terra grappler 285 which is a 33" tire but actually measures 32 1/4" on truck. No problems at all, just purchased the hyper tech speedo calibrator to keep the DIC accurate.

DTI, could you tell me the exact tire size you have? I am going to go with the Terra Grappler's myself.

bigdeer1 · January 7, 2014

I too have 3.08 with 275/65/18 Hercules mud terrain tire

divicevich · January 7, 2014

Thanks for the reply's guys, I'm still going back and forth on whether to get 33's on 18' or go with 20 inch rims.

DTI, could you tell me the exact tire size you have? I am going to go with the Terra Grappler's myself.

275/60/20

Scout_ · January 8, 2014

275/60/20

Thanks, Was the 285 size in your earlier post a typo?

SILVERADOSC540 · January 8, 2014

Whether it be 285, 265, 305 or something else, the second number in the tire size is needed along with the first to determine the overall height. My 305/40ZR22's are the same height as my winter shoes, 265/65R18's, 31.6 inches.

divicevich · January 8, 2014

Thanks, Was the 285 size in your earlier post a typo?

yep, my bad

Bbowen826 · January 11, 2014

For the GMC If you can't decide between the 3.08 or the 3.42 you can get a 3.23. Everyone thinks its only available for V6 models but that's not true. It's only available on 2wd models however.

redwngr · January 12, 2014

For the GMC If you can't decide between the 3.08 or the 3.42 you can get a 3.23. Everyone thinks its only available for V6 models but that's not true. It's only available on 2wd models however.

Must be errors in the GM online ordering guide. It still says available on V6 2wd only.

GU5 Rear axle, 3.23 ratio

1 - Standard and only available on (LV3) 4.3L EcoTec3 V6 engine with 2WD models.

Bbowen826 · January 12, 2014

Must be errors in the GM online ordering guide. It still says available on V6 2wd only.

GU5 Rear axle, 3.23 ratio
1 - Standard and only available on (LV3) 4.3L EcoTec3 V6 engine with 2WD models.

Are you looking at the Chevy or the GMC?. For the GMC you can get the 3.23 with the 5.3 2wd. Their are members on here that have it. Just go to GMC.com and look at the standard features and specs. It is listed for the 2wd V6 and V8. I'm just going off what their website says. (It could be wrong) I think for the Chevy Silverado it only comes on the V6. But since the original thread was for someone getting a GMC SIerra that was the gears I mentioned.