Info - 20 Inch Wheels and Tires Available Through GM Accessories

This bulletin is being revised to add information for setting Tire Type and Pressure for vehicles equipped with TPM. Please discard Corporate Bulletin Number 04-03-10-007D (Section 03 -- Suspension).

The purpose of this bulletin is to provide a reference guide for the technician to upgrade a vehicle from factory wheels and tires to 20" wheels and tires, which are available through GM Accessories. This guide will cover Tires, Wheels, Required Vehicle Modifications and Re-programming.

*Important: The TPC specification for the tire used on the utility vehicles (#1245 MS) is different from the tire used on the pick-ups (#1235 MS). It is important to use the proper tire with the correct TPC specification for the vehicle application.

GM has designed 20" wheels based on the Goodyear Eagle LS2 P275/55R20 tire. The Goodyear Eagle LS2 tire has a *Tire Performance Criteria spec #1245 MS (utility vehicles only). This tire has been designed to GM's specific Tire Performance Criteria. GM's Tire Performance Criteria specifications meet or exceed all Federal safety guidelines.

When mounting the tires, rubber lubricant, P/N 12345884 (in Canada, P/N 5728223), MUST be used. The vehicle should not be driven aggressively (hard acceleration or braking) for at least 6-8 hours after tire mounting to allow the lube to dry. Failure to do so may cause the tire to slip on the rim. This condition will affect wheel balance which could result in a vibration.

Spare Tire

A P265/75R16 or P265/70R17 tire should be used as a spare. Re-use the vehicle's original spare wheel to mount the spare tire. The spare tire should be used to drive the vehicle to a tire repair/replacement facility and is not intended for extended driving conditions.

Tire Changers

Dealers must have the correct level of tire changing equipment to perform tire changing services. GM requirements and recommendations for servicing glamour wheels are as follows:

For further information regarding equipment meeting the requirements for this program, call 1-800-GM-TOOLS.

Balancing

Important: Many of the 20" wheels available through GM Accessories may not be able to retain stick-on weights due to the excessive angle on the rim.

MC style coated weights are recommended and will provide the best balancing of the tire-wheel assembly. If stick-on weights are used, be sure to follow the manufacturers' recommended installation procedure (SI Document ID #664222) making sure the surface is clean and dry. Using the incorrect type of weights could result in improper fit, and such weights may fall off the wheel.

Balancing of the tire and wheel assembly must be performed on a computerized balancer, capable of static and dynamic wheel balance modes. Assemblies should be balanced to within 1/4 ounce on either rim flange. Proper cones and adapters should be used, free of nicks and burrs to ensure proper balancing.

Center Cap

Install the center cap onto the wheel after the tire has been mounted and balanced, but BEFORE the assembly is installed onto the vehicle. The preferred method for center cap installation is to push in by hand. As an alternate, use a nonmetallic object to push the center cap into place. Attempting to "hammer-on" the caps may result in damage to the cap.

Wheel (Lug) Nuts

ALUMINUM WHEELS REQUIRE SPECIAL WHEEL NUTS. Each wheel nut should be torqued in the appropriate torque sequence (refer to graphic) and to 190 N·m (140 lb ft). The torque should be re-checked after the first 160 km (100 mi). To help protect the wheels from theft, a wheel lock kit is also available.

Caution: Incorrect wheel nuts or improperly tightened wheel nuts can cause the wheel to become loose and even come off. This could lead to an accident. Be sure to use the correct wheel nuts.

Wheel Nut Caps

Install the wheel nut caps after tightening the wheel nuts. Install the wheel nut caps finger tight, plus 1/2 turn.

Care / Cleaning

Use soap, hot water and a 100% cotton cloth to clean and polish the new wheels. If using a wheel cleaner, be sure to select one that will not harm the wheel surface, such as GM Chrome and Wire Wheel Cleaner, P/N 1052929 (in Canada, use 10953202). Avoid car washes that use carbide tipped brushes, as these may damage the wheel's finish. Periodically clean the backside of the wheel to remove road grime, brake dust and grease.

Spare Tire Hoist:

Important: This modification may be necessary for the following vehicles:

Inspect the spare tire hoist. If the hoist plate partially covers the lug holes, a new spare tire hoist is required to stow the 20" wheel in the event of a flat tire. If the spare tire hoist is not changed, the hoist plate will not fit through the center of the 20" wheel and the road flat tire will have to be stowed elsewhere in the vehicle.

Tire Type/Pressure Selection:

To provide a more accurate function of the Tire Pressure Monitoring System, it is necessary to update the PDM (Passenger Door Module) with the correct tire type and pressure information. Using the Tech 2®, follow the steps listed below to select the appropriate tire type/pressure:

1. Install the scan tool.
2. Turn ignition ON with engine OFF.
3. Enter "Diagnostics" and build vehicle according to model year, vehicle line, etc.
4. Select "Chassis."
5. Select F3: Tire Pressure Monitor.
6. Select F2: Special Functions.
7. Select Tire Type/Pressure.
8. Select P-Metric Standard.
9. Select the front and rear tire pressure as noted on the new vehicle driver door placard sticker for the accessory wheels/tires.
10. Verify that the selections made are correct and press the enter key. The scan tool will flash "Procedure in Progress", then display "Procedure Complete."
11. Press the "exit" key to escape.

Tire Pressure Monitoring System:

Important: This modification is required on the following vehicles:

The Tire Pressure Monitor (TPM) system warns the driver when a significant loss of tire pressure occurs in any of the four tires while the vehicle is being driven. The system uses the passenger door module (PDM), Body Control Module (BCM), driver information center (DIC), instrument panel cluster (IPC), a radio frequency (RF) transmitting pressure sensor inside each wheel/tire assembly and the serial data circuit to perform the system functions.

If the TPM system detects a significant loss of tire pressure, or any of the tire pressures are 25% below the vehicle's recommended tire pressure, the CHECK TIRE PRESSURE warning message is displayed on the DIC and/or the low tire pressure warning indicator is displayed on the IPC, which appears as a cross section of a tire with an exclamation mark inside. Both the DIC message and the IPC indicator can be cleared by adjusting the tire pressures to the recommended kPa/psi.

The PDM (Passenger Door Module) has the ability to detect malfunctions within the TPM system. Any malfunction detected will cause the DIC to display the SERVICE TIRE MONITOR warning message.

Tire Pressure Sensors

2004 tire pressure sensors (P/N 15136883-single or 17800063-multi-pack) must be used on 2004 model year vehicles. If 2005/2006 sensors are used on a 2004 vehicle, the PDM will calculate the tire pressure value as half of the actual pressure. This will result in a low tire warning indicator being displayed. If 2004 sensors are used on a 2005/2006 vehicle, the PDM will calculate the tire pressure value correctly - no low tire warning messages will be displayed.

Important: 

To avoid system malfunctions, it is necessary to install Tire Pressure Sensors in the 20" wheels. Replacement sensors can be obtained or sensors from the OE wheels can transferred to the 20" wheels. After the wheels are installed on the vehicle, it is necessary to learn the new sensor identification codes/locations in to the PDM's memory.

The sensor learn procedure must be performed after every tire rotation, sensor replacement, or PDM replacement. Refer to the Owner's Manual or SI Document ID #1311203 for the Tire Pressure Sensor Learn Procedure.

TPM Sensor Learn Procedure -- Using Procedure From Owner's Manual

1. Set the parking brake.
2. Turn the ignition switch to RUN with the engine off.
3. Turn the exterior lamp switch from "Off" to "On" four times within 3 seconds. A double horn chirp will sound and the TPM low tire warning light will begin to flash. The double horn chirp and flashing TPM warning light indicate that the TPM matching process has started. The TPM warning light should continue flashing throughout the matching procedure. The SERVICE TIRE MONITOR message will be displayed on the Driver Information Center (DIC).
4. Start with the left (driver's side) front tire.
5. Remove the valve cap from the valve cap stem. Activate the TPM sensor by increasing or decreasing the tire's air pressure for 10 seconds, then stop and listen for a single horn chirp. The single horn chirp should sound within 15 seconds, confirming that the sensor identification code has been matched to this tire and wheel position. If you do not hear the confirming single horn chirp, you will need to start over with step number one. To let air-pressure out of a tire, you can use the pointy end of the valve cap, a pencil-style air pressure gauge or a key.
6. Proceed to the right (passenger's side) front tire, and repeat the procedure in step 5.
7. Proceed to the right (passenger's side) rear tire, and repeat the procedure in step 5.
8. Proceed to the left (driver's side) rear tire, and repeat the procedure in step 5.
9. After hearing the confirming horn chirp for the left rear tire, check to see if the TPM warning light is still flashing. If yes, turn the ignition switch to OFF.
10. Set all four tires to the recommended air pressure level as indicated on the Certification/Tire label.
11. Put the valve caps on the valve stems.

As an alternative procedure, Diagnostic tool (J 46079 -- Tire Pressure Monitor (TPM) System Diagnostic Tool) can be used to activate the sensors after a tire rotation, so the receiver can learn the new sensor locations.

TPM Sensor Learn Procedure -- Using Diagnostic Tool J 46079

1. Enable the tire pressure sensor learn mode in the receiver.
2. Starting with the left front tire, hold the antenna of the J 46079 against the tire sidewall close to the wheel rim at the valve stem location.
3. Press and release the "Activate" button. The main display will show moving waves during activation and then the sensor will transmit. The tool will display the sensor's transmission data and signal strength and a horn chirp will sound within 3-5 seconds.
4. After a horn chirp has sounded, proceed as in step 3, to the remaining 3 sensors in the following order:

•	Right Front

•	Right Rear

•

Left Rear

5. After all 4 sensors have been learned, exit the learn mode.

Deflector -- I/P Driver Knee Bolster Bracket:

Important: This modification is required for the following vehicles:

Important: A new knee bolster bracket is being installed at the Assembly Plants after the VIN breakpoints. This modification is no longer required on vehicles built after the VIN breakpoints.

Vehicles with the GM Accessory 20" wheel and GM-TPC tire system may perform differently in a frontal collision than vehicles equipped with the original equipment (OE) tires and wheels. With the modified bracket, the vehicle will meet the same Federal Motor Vehicle Safety Standard for frontal collisions as it would with OE tires and wheels.

The following procedure should be followed:

1. Apply the parking brake to prevent the vehicle from moving.
2. Remove the fuse panel cover.
3. Remove the I/P cluster trim plate bezel.
4. Remove the knee bolster.
5. Remove the 2 mm (0.078 in) thick knee bolster deflector.
6. Install the 1.5 mm (0.059 in) thick knee bolster deflector.

A detailed instruction sheet will be provided with the service kit.

Upper Rear Shock Absorber Bolt:

Important: This modification is required for the following vehicles:

Important: Shorter rear shock absorber bolts are being installed at the Assembly Plants after the VIN breakpoints. This modification is no longer required on vehicles built after the VIN breakpoints.

Both rear upper shock absorber bolts must be turned so the head of the bolt faces outward. This modification will ensure adequate clearance to the tires. The following procedure should be followed for this modification:

1. Remove the wheel-house liner to gain access to the upper rear shock absorber nut/bolt.
2. Support the rear axle.
3. Remove the rear upper shock absorber nut and bolt.
4. Reposition and install the upper shock bolts so that the head of the bolt faces outward.
5. Install the nut.

Tighten
Tighten bolt to 95 N·m (70 lb ft).

6. Reinstall the wheel-house liner.
7. Remove the support from the rear axle.

** 2003 Vehicles Equipped with Traction Control (RPO NW7) combined with a 3.42 Axle Ratio (RPO GU6)

Important: The 2004 ABS module is not compatible with the brake systems of the 2000-2002 model year vehicles.

2003 Model Year vehicles ONLY , may be equipped with 20" wheels if the EBCM (Electronic Brake Control Module) is replaced. The 2004 EBCM should be installed. This module will NOT work on 2000-2002 Model Year vehicles. Failure to replace the EBCM will cause DTC C0279 to set.

Tire Label:

After installing the recommended P275/55R20 tires, place the provided tire label on the vehicle. The tire label should be located on the door jam, near the original tire label, and should not cover up the original tire label. Be sure that the surface is clean and dry. The surface temperature should not be less than 21°C (70°F). The label is provided as a guide for tire inflation pressures and information relevant to occupant/cargo capacities.

Owner's Manual Insert:

An Owner's Manual insert (Buying New Tires for Plus-Size Wheels) is provided to give instructions for the selection of proper replacement tires. Place the insert in the Owner's Manual over the original "Buying New Tires" instructions.

Important: For proper vehicle operation and to insure coverage under the provisions of the new vehicle warranty, the vehicle must be reprogrammed with the correct calibration as soon as the 20" wheels are installed.

It will be necessary to reprogram the PCM for speedometer accuracy. Contact Techline (1-800-828-6860 English or 1-800-503-3222 French) to obtain a VCI number. Then refer to the table below for the appropriate calibration part number based on the model year and axle ratio.

Calibration Information Documentation

1. Make a copy of the "Accessory Wheel and Tire Information Form" included in this bulletin.
2. Provide all information required on the form.
3. Make a copy of the completed form for the customer to keep in the vehicle along with their Owner's Manual.
4. File the original completed form in the Dealership's Vehicle Service History folder.

Important: Because this is not a warranty repair, dealers will incur a charge to obtain a VCI number.

Important: A VCI number will not be available for vehicles equipped with the following options:

There is a tire size value in the ABS module that must also be updated using the Tech 2. Use the following path to update the ABS module: Diagnostics>Model Year>Vehicle Type>Chassis>Product Line>GVW>ABS>Special Functions>Tire Size Calibration>Verify VIN>Select New Tire Size.

Important: If original equipment tires/wheels are reinstalled, it will be necessary to reset the programming of the PCM and the ABS module to the original specifications. For those vehicles equipped with VSES, it will be necessary to update the tire size in the VSES module.

This section applies only to those vehicles equipped with Vehicle Stability Enhancement System (VSES) -- RPO JL4.

The characteristics of a specific vehicle, that affect vehicle handling or input signals to the electronic brake control module (EBCM), ultimately determine how the VSES operates. Adaptive learning is accomplished by maintaining a yaw rate sensor/lateral accelerometer data table in the EBCM memory. As the vehicle is operated, the table is populated with data that is later referenced, and sometimes modified, to allow the EBCM to provide the best possible stability control for the specific vehicle.

Important:  Different size tires may cause the data stored in the table to become unreliable. Therefore, the yaw rate reference table reset procedure must be performed.

The following procedure should be followed to reset the yaw rate reference table. This procedure should only be used on vehicles equipped with VSES -- RPO JL4.

1. Turn OFF the ignition.
2. Disconnect the yaw rate sensor/lateral accelerometer harness connector.
3. Start the engine.
4. Apply firm and steady pressure to the brake pedal for at least 10 seconds.
5. Turn OFF the ignition.
6. Reconnect the yaw rate sensor/lateral accelerometer harness connector.
7. Turn ON the ignition and use the scan tool to clear the DTCs.

Wheels

All GM Accessories sold and permanently installed on a GM vehicle PRIOR to new vehicle delivery will be covered under the provisions of the New Vehicle Limited Warranty.

For the U.S., in the event GM Accessories are installed AFTER the New Vehicle Delivery, or are replaced under the New Vehicle Warranty, they will be covered (parts and labor) for the balance of the vehicle warranty, but in no event less than 12 months/12,000 miles. This coverage is only effective for GM Accessories permanently installed by a GM dealer or a GM approved ADI (Accessory Distributor / Installer).

For Canada, in the event GM Accessories are installed AFTER the New Vehicle Delivery, they will be covered (parts and labor) for the balance of the vehicle warranty, or up to 12 months/Unlimited kilometers depending on month installed. For replacement under New Vehicle Warranty, refer to claim type "B" guidelines.

GM Accessories sold over-the-counter, or those not requiring installation, will continue to receive the standard GM Dealer Parts Warranty of 12 months from the date of purchase (parts only).

Tires

Any approved tire installed on a GM Vehicle PRIOR to delivery will be covered under the provisions of the New Vehicle Limited Warranty. Tires are covered against defects in material and workmanship. Tires are warranted for defects "without" prorated charge for tread mileage. Subsequent replacements under this warranty will continue to be covered for the remainder of the New Vehicle Limited Warranty.

Any approved tire installed on a GM Vehicle PRIOR to delivery may continue to be warranted on a prorated basis by the tire manufacturer once the New Vehicle Limited Warranty expires.

Any approved tire installed AFTER delivery will be covered under the provisions of the tire manufacturer warranty.

USA dealers should refer to GM Warranty Administration Bulletin 00-03-10-003I and GM Parts Process / Policy Bulletin IB03-001 for more information.

Canadian dealers should refer to GM Warranty Administration Bulletin 01-03-10-003B.

Only GM dealerships have the ability to file warranty claims for GM Parts and Accessories. Therefore, any warranty claims filed against such parts must be handled by the servicing GM dealership. This includes those parts purchased from a GM-approved ADI (Accessory Distributor / Installer).

You have just modified your vehicle by installing an "Accessory Package" which includes Wheels and Tires. This form contains important information about your accessory installation. In an effort to provide superior service to you, our customer, we ask that you please present this form to your Servicing Dealer when removing or installing wheels and tires on your vehicle. This form contains important information necessary to service your vehicle.