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2017 Silverado LTZ Z71
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4,930 Posts
Discussion Starter · #1 ·
Hello all,

I am considering putting 285/70r17's on my sierra when the stock goodyears wear out. I am only concerned with the 3:42 axle ratio. Would i be okay keeping it with 285s? or would i need to upgrade to a 3:73?
I live in Houston, TX. mostly city and highway driving. Mpg is important to me right now. I don't own a trailer, so i dont tow with it. I've only towed once with it.

what should i do?
 

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2009 Silverado LT 4WD
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9,464 Posts
You'll be fine with 3:42's and 285/70/17's...only reason I would suggest that you get 3:73's would be if you tow. As far as mpg's going to 3:73's I don't think would help much, I lost 2 mpg's when I went to 285/70/17's and I have 3:73 gears...I average 16/17 mpg's now with CAI/tune on 93 octane...
 

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2017 Silverado LTZ Z71
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4,930 Posts
Discussion Starter · #4 ·
Wow 16 / 17 mpg is far better than what i am getting right now! i'm averaging 14 mpg. i'm beginning to think it was the throttle body spacer i put in that is screwing me on the mileage.
 

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2009 Silverado LT 4WD
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9,464 Posts
Remember I have a tune which added around 2 mpg's to my truck. Before I was about where you at with mpg's. If your only concern with gear change is mpg's I would look into tuners instead.
 
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