Info - 20 Inch Wheels Available Through GM Accessories

This bulletin is being revised to include 2007 model year and calibration information. Please discard Corporate Bulletin Number 03-03-10-006E (Section 03 -- Suspension).

Excludes 1999-2000 vehicles with 4.3L (VIN W -- RPO L35) engine.

*Excludes vehicles with Traction Control combined with 3.42 Axle Ratio (RPO NW7).

** Excludes 2WD Crew Cab built prior to:

** Excludes 4WD Crew Cab built prior to:

** Excludes AWD Crew Cab built prior to:

-- Sierra Denali built prior to VIN breakpoint 51334762

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 (dealers must confirm availability of parts prior to utilizing this bulletin). This guide will cover Tire Specifications, the Spare Tire, Balancing, Center Cap Installation, Wheel Nuts, Re-Programming and Label requirements.

GM has designed 20" wheels based on the Goodyear Eagle LS and LS2 P275/55R20 tire. The Goodyear Eagle LS tire has a Tire Performance Criteria spec #1235 and the LS2 has a Tire Performance Criteria spec #1245. These tires have 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.

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.

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.

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 will 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.

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.

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.

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

Important: This modification is required on all 2WD vehicles EXCEPT the following:

It will be required to replace the existing front suspension spring/jounce bumper with Jounce Bumper kit, P/N 12499481. The following procedure should be followed:

1. Raise and support the vehicle.
2. Remove the nut from the spring bumper stud.
3. Remove the spring bumper.



4. Install a new spring bumper assembly for 2WD 1500 Series Only with 20" wheels.
5. Reuse the nut from the original bumper. Install the nut to the spring bumper stud.

Tighten
Tighten the nut to 30 N·m (22 lb ft).

6. Remove the safety stands.
7. Lower the vehicle.

Important:  This modification is required for the following vehicles and ONLY applies to Extended Cab Long Box (K15953) Pickup models:

1999-2005 Chevrolet Silverado and GMC Sierra (1500 Series Only):

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, P/N 12499966.

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

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 only be available for the following models:

Important: 

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.

After installing the recommended P275/55R20 tires, place the provided label on the vehicle. The label should be located on the door jamb, 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.

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 after the new vehicle warranty expires, but within the 12 months/unlimited kilometers coverage, 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.