Beware installing a lift or bigger tires on your T1 !

[Rob41]

I went to the dealer today to have them reprogram my speedo the largest size the OEM offers now that I've got 35's installed.  They tried to get the code from GM to allow them to do it but GM flat out refused.

 

I called dealerships in Saginaw, Midland, Mt Pleasant, Traverse City, Alpena, and a couple others I can't remember and they all told me the same thing, that they cannot re-calibrate the speedo as GM won't allow them to do so.

 

Lessons learned:

1. Take what is frequently stated as fact on forums with a grain of salt.

2. Understand the Magnuson-Moss act does not cover lifts and bigger tires.  They cannot outright nullify your warranty, but can and do deny specific repairs citing what you did lead to the failure.

3. The MM act, SEMA attornies, lift companies, wheel and tire outlets and others are not lying when they say it doesn't void your warranty, but as stated above, they can and do deny specific claims citing your mods caused the failure.  Good luck fight GM in court.

4. When your dealer tells you they will take care of you, you really don't know that until something needs to be replaced.  Even if they intend to take care of you, their hands may be tied by GM.

 

My dealer wants to help me and the owner is even checking with a friend who added larger tires to see what he did.  I think I'll be getting an in-line programmer and cross my fingers that it really doesn't leave any traces behind.

 

If anyone has a dealer that can reprogram the speedo (in Michigan) I'd like to hear about it.  Not just those trucks like Black Widow that carries a secondary warranty, and on the T1.

[Texanfisherman]

An option::

Hypertech

Speedometer Calibrators Inline - Part #730129

[Rob41]

1 hour ago, Texanfisherman said:

An option::

Hypertech

Speedometer Calibrators Inline - Part #730129

That's what I'm looking at but so far I haven't found any reviews.  I'm surprised nobody here has used one yet given how many people have put bigger tires on their T1's.

[foxcoupefan]

You will read 4mph slow. Just keep that in mind for oil change intervals and or speed limits and you are good! 

 

 

I have owned 58 vehicles in my life and have never been denied a warranty claim due to wheels and tires of any size. Never have I had a warranty issue deemed to be caused by wheels, tires or suspension. 

 

 

[Rob41]

I'll likely end up getting the Hypertech speedo calibrator as I'm not going to have my speedo reading 5 mph off at highway speeds.

[newdude]

Dealer and GM will be of no help in the end.  GM will only authorize recalibrations for factory sized equipment.  So if the truck had 17" wheels and you wanted the factory 22" wheels (going from a 31" tire to 33" tire), GM has a calibration for that.  It has been this way for years.   

 

Aftermarket will be your only option. 

Edited August 8, 2019 by newdude

[Texanfisherman]

That's what I'm looking at but so far I haven't found any reviews.  I'm surprised nobody here has used one yet given how many people have put bigger tires on their T1's.

Many of the lifts that I have seen include such things so there are no issues when they roll off the lot I won’t be installing my lift until the spring, but I will be installing that adapter if a better device doesn’t come along first. Seems like a straight forward, simple fix. I would expect shops like 4wheel parts have installed them for sure. Might drop them a line or give a call.

 

 

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[Trailboss75]

My dealer said to bring it in and they would do it for me.  $300 for device and for them to reprogram. Just haven’t done it yet cause I didn’t want to spend $300 for slightly larger tires.

[HeySkippyDog]

It's entirely possible to reprogram it, just buy the tuner.

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[Rob41]

Obviously someone who didn't read the posts in the thread, lol.  ^^

Edited August 9, 2019 by Rob41

[Sotally Tober]

Hypertech works perfectly for me.  Haven't touched it since set up 4 months ago.  

[Rob41]

1 hour ago, Sotally Tober said:

Hypertech works perfectly for me.  Haven't touched it since set up 4 months ago.  

Oh cool, did you install it?

[airborne89]

So what is the largest tire that GM offers on these trucks?  My current factory tires are 275/60 R20, does GM offer anything larger they will reprogram the spedo for?  Thanks

[dctackett10]

If a ball joint fails or suspension and you don’t have a lift. Just install factory tires and bring it back in to the dealership lol.

[Rob41]

8 hours ago, airborne89 said:

So what is the largest tire that GM offers on these trucks?  My current factory tires are 275/60 R20, does GM offer anything larger they will reprogram the spedo for?  Thanks

Initially my dealer said they could only reprogram to the largest size offered on my model T1 which I think is the 275/50R22, could be wrong on that though.

 

Once at the appointment, they said they couldn't even do that because GM wouldn't release the code to do it.