what rear gear?

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Jun 19, 2015 | 07:50 AM

dsadsdaiouser

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what rear gear?

Can anyone tell me what rear gear is in our 2012 GMC Sierra 1/2 ton extended cab 2WD? Here is the tag in the glove box:

Thanks.

Scott

Jun 19, 2015 | 08:11 AM

98CayenneT/A

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From: White Bear, Mn

Gu6 = 3.42

Jun 19, 2015 | 07:09 PM

dsadsdaiouser

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Thanks! We changed from a 245/70/17 tire to an OEM wheel and 275/55/20 tire and even though the circumference only increased 4.4" I'm surprised how lazy it feels now. Acceleration is terrible and it feels down on power. Maybe we need to look into a 3:73 or 4:10 gear?

Scott

Jun 19, 2015 | 07:36 PM

98CayenneT/A

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4 in. taller is actually a lot and will kill your acceleration, if you're going to do a gear change go with the 4.11's

Jun 23, 2015 | 06:58 AM

A-Dub

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Quote:

Originally Posted by 98CayenneT/A

4 in. taller is actually a lot and will kill your acceleration, if you're going to do a gear change go with the 4.11's

Its not 4" taller, he said circumference, not height...

The 275/55 20 is roughly 1.4" taller than the 245/70 17.

OP, the difference you are seeing is primarily the rotating weight, not so much the diameter change. the 20" wheel and tire weighs a lot more than the 17s did. It affects acceleration and mileage. FWIW, Id get a tune before I changed gears.

Jun 23, 2015 | 04:01 PM

dsadsdaiouser

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Quote:

Originally Posted by A-Dub

Thanks! Good idea. I thought of that too. The tuner locally that handles our C5 said he'd be glad to do the truck and could help out the power and mileage.

Scott