I put 265's on my 05 2500HD Dmax and took it to the dealer to recalibrate the spedo.......what they ended up doing was recal the abs module for the new 265 tires.......did they recal for the abs or for my spedo? Anyone know?

Thank you

Dealer can't do the re-cal, you need a Predator or something similar for that. Re-cal on the ABS is all we can do, and it doesn't do any good unless the PCM is calibrated to match.

thanks! How should I check to see if they recal'd the PCM? My service notes say nothing about it......

Sorry max, but starting in 04 the dealers can reprogram for almost any tire size. you call tech line and get a VCI number that programs PCM EBCM TCM BCM and IPC

Sorry max, but starting in 04 the dealers can reprogram for almost any tire size. you call tech line and get a VCI number that programs PCM EBCM TCM BCM and IPC That is a good idea, get a VCI # so that GM has documented proof of oversize tires and a reason to deny warranty claims... Been there, seen that. They are weasels.

Max, glad you are in Oregon, a little south in LA LA land we have and G.M. has technology that doe's not void your warranty. post when you know not when you don't!!!!

I am posting what I do know...but you must know more than I do. Why keep it a secret? I believe this forum was created to HELP people, not for you to come on here with all of your 28 most helpful posts and be a prick. So explain to me how you get a VCI# without GM knowing about it... That would be helpful :D (a little background... our dealership ate a warranty claim on an Allison repair due to the fact that we had gotten a VCI# at the customers request to calibrate for 265's. They provided us with bulletin #01-03-10-010D, and told us to have a nice day) So it looks like we need to refresh ourselves on a few bulletins...

95-05 All General Motors Light Duty Trucks/Utilities Guidelines to Change Tire Size - kw wheel rim size calibration #PIT3271 - (Nov 12, 2004)
95 - 05 All General Motors Light Duty Trucks/Utilities Guidelines to Change Tire Size
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The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:
Changing of tire size on midsize and fullsize trucks and utilities.

Recommendation/Instructions:
When attempting to change tire size, it is important to understand what tire size the customer is interested in installing. 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. DO NOT use the information offered in the ABS module (tire size selection) as a guide to see what tires are applicable to the vehicle in question. Keep in mind, changing the tire size in the ABS module will only affect ABS wheel speed sensor calibration that are direct inputs to the ABS module. It will not correct or calibrate the speedometer's accuracy, and will not change the calibration of the ABS rear speed sensor value on vehicles that obtain rear wheel speed data from the ECM/PCM/VCM via the VSS.

Example.

2004 Chevrolet Colorado LS with 235/75/R15 tires. The customer would like to install P265/75/R15 tires. Although ABS module shows this tire can be programmed, the 265/75/R15 will only fit under a Colorado with the Z71 suspension. This suspension will offer acceptable wheel clearance. Therefore, a calibration will not be offered for this application.

The only way to confirm that a calibration is available would be to visit YOUR sales department. DO NOT CALL Technical Assistance or Techline to search for your application or usage. Using the sales order guide, the following combinations of items must be available for the vehicle in question... If you can build a vehicle, using the sales guide, using the same model year, body style, engine size, transmission type, axle type and suspension type, any tire offered for that combination will be offered a calibration. The only other way a calibration will be available is if GM Accessories releases an approved tire wheel combination that has been tested and validated by GM Engineering for a specific application. An example of this would be bulletin 03-03-10-006a, which offers 20" wheels and tires for the full size pick up trucks. A calibration has been developed for this specific application in response to popular demand from our customers.

Once the tire application has been confirmed per the sales guide, contact Techline at 800-828-6860 for a VCI Number. Please note, there may be a cost to the customer for this service. This is not a feature that is covered under the manufacturers warranty.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:
(95 - 05 All General Motors Light Duty Trucks and Utilities)

Info - Inspection of Tire and Wheel Size Prior to Diagnosis of Transmission Shifts, Poor Performance, Speedometer, Cruise Control Concerns #01-03-10-010D - (Aug 31, 2004)
Inspection of Tire and Wheel Size Prior to Diagnosis of Transmission Shifts, Poor Performance, Speedometer, Cruise Control Concerns
2001-2005 Chevrolet Silverado Pickup Models

2001-2005 GMC Sierra Pickup Models

with Allison® Automatic Transmission

This bulletin is being revised to add the 2005 model year. Please discard Corporate Bulletin Number 01-03-10-010C (Section 03 -- Suspension).

Proper diagnosis of engine, transmission, speedometer and cruise control concerns must begin with an inspection of tire/wheel size.

The 2500 series trucks have LT245/75R16E tires as standard equipment.
The 3500 series trucks with dual rear wheels have LT215/85R16D tires as standard equipment.
The 3500 series trucks with single rear wheels have LT265/75R16E tires as standard equipment.
A truck that has different tires and wheels will have engine power/performance concerns, transmission shift concerns, speedometer registered speed concerns and cruise control concerns.

Before any diagnosis is performed for these types of concerns, inspect the tires/wheels for the proper tire and wheel combinations.

If a truck is found to have other than the above listed tire sizes, no further diagnosis should be undertaken until the original size tires and wheels are reinstalled on the truck.

The Engine Control Unit (ECM) and Transmission Control Module (TCM) use (RPM) and (VSS) inputs as operational parameters for engine torque, transmission shifting, cruise control operation and speedometer indicated vehicle speed.

Calibrations for different tire/wheel combinations are not available.

Therefore, changing of tire and/or wheel size should not be undertaken by dealerships or truck owners.

Warranty Information
Reinstalling the proper wheels and tires on the vehicle, prior to performing any type of diagnosis of the truck, would be considered truck owner responsibility and not a warranty repair.