Dealer/Warranty Concerns if swapping wheels/tires over to other factory available size?

[Ricky_Starbucks]

4 hours ago, chieffie said:

DEALER WOULDNT DO A RECALIBRATION ON MY 19 THAT CAME WITH 18 INCH RIMS, I PUT THE FACTORY 20 INCH LTZ RIMS AND TIRES ON AND THEY SAID THEY HAD NO CALIBRATION FOR THE TRUCK, MY TRUCK AN LT 5.3 8 SPEED 3.23 REAR

Yeah.  Im at war with the dealership I purchased my vehicle from. They  said they contacted GM and since my truck has a 17" spare they wouldn't do it.  I had previously contacted a closer dealership and they said no problem, just recommended an alignment (which I know I don't need as no suspension adjustments are being made) and they want to charge mounting/balancing even though the wheels/tires I am coming with are already all set.  They said since they still have to physically mount the wheels to the truck they need to charge the $120 for it.  $79.95 for the recalibration is what I was quoted.

 

Rick

[Ricky_Starbucks]

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Edited December 29, 2021 by Ricky_Starbucks
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[Ricky_Starbucks]

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Edited December 29, 2021 by Ricky_Starbucks
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[redwngr]

This can be used to see how close the OD's of the factory tires are to each other. 

 

What matters is the tire OD (and revolutions per miles) not the diameter of the rims.

 

https://tiresize.com/comparison/

[TxTruckMan]

Recalibrating for similar tires sizes is a complete waste of money.  It's not even required for drastic tires size differences.  Just remember that you'll be going 3-5 MPH faster at 70 and you're good to go.

[Dunn]

On 12/23/2021 at 10:52 AM, newdude said:

 

 

 

ALSO.

 

T1 trucks.  If you have 17s or 18s from the factory, GM has flashes to install the accessory 20s and 22s.  They flash the ECM, BCM, Power Steering and Front Camera Module if it has one.  

 

But I guess GM must be lying there too...

if you buy the trail boss GM lift they also reprogram at dealer

[newdude]

On 12/28/2021 at 7:25 PM, Ricky_Starbucks said:

Yeah.  Im at war with the dealership I purchased my vehicle from. They  said they contacted GM and since my truck has a 17" spare they wouldn't do it.  I had previously contacted a closer dealership and they said no problem, just recommended an alignment (which I know I don't need as no suspension adjustments are being made) and they want to charge mounting/balancing even though the wheels/tires I am coming with are already all set.  They said since they still have to physically mount the wheels to the truck they need to charge the $120 for it.  $79.95 for the recalibration is what I was quoted.

 

Rick

 

 

All the spares are 17 inch on 1500s.  Just the tire size changes based on the wheels and tires its built with and has a matching diameter full size tire just in a 17 inch rim fit.

 

If the truck was built with 255/70R17 comes with a matching 255/70R17 spare.

 

If the truck was built with 265/70R17, 265/65R18 or 275/65R18, the spare is a 265/70R17. 

 

If the truck was built with 275/60R20 or 275/50R22, the spare is a 255/80R17.  

 

So their excuse saying "its a 17 inch spare" is largely incorrect.  The tire size is the issue as it wouldn't be a matching spare, but all you'd have to do is put a corresponding tire from the 3 choices above.  

Edited January 2, 2022 by newdude

[Ricky_Starbucks]

I finally just heard back from the dealer on trying to get my speedo recalibrated for AT4 wheels and it was a no go.  the AT4 has 275/60/20 whereas the 20" option on the Silverado was 265/60/20 so they were "told by GM" there was "no software" for this combination on my vehicle.

 

Trying to decide if I want to risk going with a Pulsar or not, though my truck is brand new and I want no Warranty issues if I should need to use Warranty Service.

[TxTruckMan]

2 hours ago, Ricky_Starbucks said:

I finally just heard back from the dealer on trying to get my speedo recalibrated for AT4 wheels and it was a no go.  the AT4 has 275/60/20 whereas the 20" option on the Silverado was 265/60/20 so they were "told by GM" there was "no software" for this combination on my vehicle.

 

Trying to decide if I want to risk going with a Pulsar or not, though my truck is brand new and I want no Warranty issues if I should need to use Warranty Service.

You are worried about nothing.  Just get the tires you want and forget about it.  I have never heard of anybody having a warranty claim denied because of a tire change.  Certainly not a 5% taller tire.  5% taller means you're going 5% faster.  100->105 MPH. 50MPH -> 52.5 MPH.  60 -> 63 MPH. 70 MPH -> 73.5 MPH.  It's not that complicated.

 

I bet that there's no software available because all GM trucks use the same speedo calibration for all of their trucks regardless of tire size.  Your tire wears down 5% in height over the life of the tire.

Edited January 27, 2022 by TxTruckMan

[fastk9dad]

On 1/27/2022 at 3:15 PM, Ricky_Starbucks said:

I finally just heard back from the dealer on trying to get my speedo recalibrated for AT4 wheels and it was a no go.  the AT4 has 275/60/20 whereas the 20" option on the Silverado was 265/60/20 so they were "told by GM" there was "no software" for this combination on my vehicle.

 

 

Here is the relevant TSB (PIT3271K) and specific text:

https://static.nhtsa.gov/odi/tsbs/2020/MC-10184105-9999.pdf

 

General Motors will ONLY support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications.  The only way to confirm that a calibration is available would be to visit YOUR sales department.  Using the sales order guide, if you can build a vehicle, using the same make, model year, trim, and meet any restrictions listed in the tire section, GM will have a corresponding calibration available.

[newdude]

On 1/27/2022 at 3:15 PM, Ricky_Starbucks said:

I finally just heard back from the dealer on trying to get my speedo recalibrated for AT4 wheels and it was a no go.  the AT4 has 275/60/20 whereas the 20" option on the Silverado was 265/60/20 so they were "told by GM" there was "no software" for this combination on my vehicle.

 

Trying to decide if I want to risk going with a Pulsar or not, though my truck is brand new and I want no Warranty issues if I should need to use Warranty Service.

 

 

That's because the Trail Boss doesn't come with 275/60R20 anymore and its not an option on it.  Tires are 275/65R18 or 265/60R20.  AT4 can still get the 275/60R20 so going from factory equipped 18s to the AT4 optional 20s would be an option for an AT4 owner.

 

That said, 265/60R20 is 32.6" tire, 275/60R20 is 33" so if you want to switch to that size, there is no need to program.  Your speedo will be off 0.5mph, not enough to worry about programming or a Pulsar.  

[fastk9dad]

On 1/27/2022 at 6:10 PM, TxTruckMan said:

I bet that there's no software available because all GM trucks use the same speedo calibration for all of their trucks regardless of tire size.  Your tire wears down 5% in height over the life of the tire.

 

You'd think someone on here would be able to confirm exactly how many calibrations they have. Are they just using average revs for say all 18" tires for a specific model or do they use specific revs for each. Didn't GM tout the that AT4/TrailBoss could fit 35's stock when it was released? Yet they provide no way to adjust the speedo accordingly?

 

I wonder what dealers do that sell brand new modified trucks with larger than spec'd tires. Do they just let it ride? or are they using something like the Hypertech?

[newdude]

On 1/27/2022 at 6:10 PM, TxTruckMan said:

I bet that there's no software available because all GM trucks use the same speedo calibration for all of their trucks regardless of tire size.  Your tire wears down 5% in height over the life of the tire.

 

There is indeed.  Even the factory 20" and 22" accessory wheels have programming that needs to be done if the truck came stock with 17s (255/70 30.5" tire or 265/70 31.5" tire) or 18s (265/65 31.5" tire).  The 20s and 22s are 33" tires and the programming is done for 3 things:

 

- ECM for speedo

 

- BCM

 

- EPS module (Electronic Power Steering) to change PS assist calibrations

 

- Front Camera Module (if equipped) because any safety equipment on the truck that uses the camera is dependent on correct wheel speed based on the truck's tire calibration.  Larger tires from stock without flashing this can cause forward collision, lane departure, etc. malfuctions.

 

[newdude]

1 minute ago, fastk9dad said:

 

You'd think someone on here would be able to confirm exactly how many calibrations they have. Are they just using average revs for say all 18" tires for a specific model or do they use specific revs for each. Didn't GM tout the that AT4/TrailBoss could fit 35's stock when it was released? Yet they provide no way to adjust the speedo accordingly?

 

I wonder what dealers do that sell brand new modified trucks with larger than spec'd tires. Do they just let it ride? or are they using something like the Hypertech?

 

 

They don't offer 35s from the factory or as an accessory hence no calibration.  If GM launched a 35" accessory tire option, there would be a cal file.

 

There is 3, possibly 4 calibrations GM uses going off their chart.  There is a calibration for 255/70R17 base tire, a calibration for 265/70R17 option tire, one calibration for both 265/65R18 and 275/65R18, and then one both for 275/60R20 and 275/50R22.

[fastk9dad]

4 minutes ago, newdude said:

They don't offer 35s from the factory or as an accessory hence no calibration.  If GM launched a 35" accessory tire option, there would be a cal file.

 

Understood, and it's too bad they don't offer that combo, probably due to EPA and mileage I would suspect. What gets me is they touted larger tires but then offer no way to get there calibration wise.

 

6 minutes ago, newdude said:

There is 3, possibly 4 calibrations GM uses going off their chart.  There is a calibration for 255/70R17 base tire, a calibration for 265/70R17 option tire, one calibration for both 265/65R18 and 275/65R18, and then one both for 275/60R20 and 275/50R22.

 

Thanks for that, sort of confirmed my suspicions.