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Posted

 

 

I've been lurking here for a while but figured i'd throw my new truck in the mix. 2016 Sierra Denali 6.2 4x4 all stock with the exception of BFGoodrich All Terrain T/A KO2 tires in 275/60R20 and drop in K&N filter. No lift, no level, no scrubbing at all.

 

 

 

 

 

 

Looks nice! Congrats on the truck and welcome!

 

Sent From My Galaxy S6 Edge+

  • Like 1
Posted

They are 285 65/20's The Texas Edition comes with 20's but the dealer went with the oversized tires on them. I love the tires but my speedo is off by 5mph. Dealer wont re-calibrate the speedo.

Posted

They are 285 65/20's The Texas Edition comes with 20's but the dealer went with the oversized tires on them. I love the tires but my speedo is off by 5mph. Dealer wont re-calibrate the speedo.

I've read (and been told by dealers) that the dealer will not recal the speedo unless its with a factory optional size. My speedo is off when I put on 275/60/20s but i recently bought a hypertech speedo recal. Not the power programmer but just the tire/gear speedo recal. Got it for about 175$ from an online store with free shipping (PM me if u want to know which), cheapest i could find. It works well and don't have to worry about voiding warranty as I'm told the newer trucks computer keeps logs of all changes and they can void your warranty if something goes wrong after using a power tuning programmer. There are documented exceptions to this but personally for a few HP i'm not risking the warranty. I'm a programmer by trade and its amazing how much and what can be recorded these days.

Posted

They are 285 65/20's The Texas Edition comes with 20's but the dealer went with the oversized tires on them. I love the tires but my speedo is off by 5mph. Dealer wont re-calibrate the speedo.

 

 

I've read (and been told by dealers) that the dealer will not recal the speedo unless its with a factory optional size. My speedo is off when I put on 275/60/20s but i recently bought a hypertech speedo recal. Not the power programmer but just the tire/gear speedo recal. Got it for about 175$ from an online store with free shipping (PM me if u want to know which), cheapest i could find. It works well and don't have to worry about voiding warranty as I'm told the newer trucks computer keeps logs of all changes and they can void your warranty if something goes wrong after using a power tuning programmer. There are documented exceptions to this but personally for a few HP i'm not risking the warranty. I'm a programmer by trade and its amazing how much and what can be recorded these days.

 

How are you finding out that your speedo is off? Thought I found, in the vehicle settings, a way to adjust the speedo. When I had found it, I thought it was cool. Then I went to a lot of the known speed indicators, in school zones and a few "hot spots" on Edwards AFB, to see how accurate my speedo was/is right out of the store. Some were showing about 0.5MPH, but most were showing dead on.

 

If I stumble across it again, while playing with my vehicle settings, I'll post the directions to get to it.

Posted

There is no way to change it yourself...the speed is from my GPS...GPS shows 70...speedo shows 65. Get a GPS and you will see yours off for sure if you have oversized tires. Guaranteed.

  • Like 1
Posted

 

 

 

How are you finding out that your speedo is off? Thought I found, in the vehicle settings, a way to adjust the speedo. When I had found it, I thought it was cool. Then I went to a lot of the known speed indicators, in school zones and a few "hot spots" on Edwards AFB, to see how accurate my speedo was/is right out of the store. Some were showing about 0.5MPH, but most were showing dead on.

 

If I stumble across it again, while playing with my vehicle settings, I'll post the directions to get to it.

 

I'm using a gps speedometer app on my phone. GPS is pretty accurate as long as you get good signal and stay at a steady speed. I've also done the math based on gears and actual tire size etc but primarily the former.

Posted

Hmmm. What is your tire size? If it's an oversized tire like mine, it will be off.

 

I'm sure someone will chime in on this but the factory calibrates the tore size at the factory for the specific tire. I don't believe it has much to do its transmission gear ratio but more so the rotation of the tire. I may be mistaken.

 

To recalibrate the speedo takes an act of God from chevy and they will not recalibrate for an oversize tire install. I can tell you that the harmin gps on the highway differs from my speedometer. I'll get a cop buddy to radar me soon.

 

Thanks for the insight.

Posted

I've also read that GM calibrates all of the speedos in the K2s(at least 1500s but maybe the HDs also) to one size no matter what factory size you have. They calibrate them to 265/65/18. But, being that they're all very close in circumference that it's not a big enough difference to really matter. In fact I believe it helps the owner since the odometer will read lower than the actual miles.

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