21-NA-270

Bulletin No.:
Service Bulletin
Date:
21-NA-270
November, 2023
INFORMATION
Subject:
Vibration Caused by Tires
Brand:
Model:
Chevrolet
Silverado 4500HD/
5500HD/6500HD
Model Year:
from
to
2019
2023
VIN:
from
Engine:
Transmission:
to
Involved Region or Country
United States
Condition
Some customers may comment on a vibration while driving.
Cause
The cause of the condition may be that the wheel and tire assemblies require Road Force
balance.
Verify the vibration is from the tires by using Pico scope (NVH) and attach to the
workorder.
Note: Before using the PICO drive the vehicle 15 to 20 minutes to help reduce the effect
of tire flat spots from sitting.
1. Lift and support the vehicle and remove the wheels. Refer to Tire and Wheel
Removal and Installation in the Service Manual.
2. Using the hunter Road Balancer, the wheel/tire assembles runout should be
measured and the high spots identified and marked. The front tires should have a
RFV less than 50 lbs.
3. Once these are measured, the tire pairs should be reinstalled with the high spots
clocked 180 degrees from each other.
4. Before tire replacement, follow the match mounting tire to the wheel assembles
called out in Bulletin 02-03-10-005C, record the findings.
Note: For wheel/tire assemblies above 75 lbs RFV clocking the high spots 180 degrees
may not provide enough reduction in vibration. Drive to determine, and replace rear tires
as needed to achieve required RFV per wheel tire assembly.
Correction
Copyright 2023 General Motors LLC. All Rights Reserved.
5. Record the RFV for each tire wheel assemble and attach to the work order.
• RF• LF• RRO• RRI• LRO• LRI• Runout specification is 0.055
6. For Goodyear tires Record the runout for each tire wheel assemble and attach to
the work order.
• RF• LF• RRO• RRI• LRO• LRI• Runout specification is 0.055
If a tire needs to be replaced, follow Bulletin 20-NA-159 for warranty Administration, as
only the tires that are out of specification should be replaced.
Page 2
November, 2023
Bulletin No.: 21-NA-270
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.
Service Procedure
6473695
Adding masking tape to the centering ring to help with
the Center Checking procedure. There is 2 layers of
tape (2 times around). This especially helps with
stamped steel wheels.
With this common setup, the Roadforce Roller does not
fully contact the tire tread.
6473693
Helpful hints when using the 20-2977-2 (8 lug 19.5 inch
stud kit.
This is the common setup for MD wheels on the
Hunter 9700.
Bulletin No.: 21-NA-270
November, 2023
6473696
With the addition of this spacer, it will allow the
Roadforce roller to fully contact the tire tread.
Page 3
6473697
Here you can see the roller against the tire. With doing
this, it reduced the Roadforce 9 Lbs. Nothing was
changed with the process or tire/wheel assembly.
Now the tire and rim can be marked. Rotate the tire on
the rim and retest. This may help reduce the Roadforce
if below 50. Balance the tire and reevaluate the
customers concern with the PICO.
Page 4
November, 2023
Bulletin No.: 21-NA-270
Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information:
Labor Operation
Description
Labor Time
*8080688
Verify Vibration and Measure and Mark High Spot of the
Wheels
0.6 hr
Add
To Measure - Each Additional Wheel
0.3 hr
*This is a unique Labor Operation for Bulletin use only.
Version
5
Modified
Released November 19, 2021
Revised July 26, 2022– Added 2022 Model Year, added steps to Correction Section,
added Important statement under Service Procedure, and added Warranty Information
with Labor Operation.
Revised August 23, 2022 – Added runout specification to Correction Section
Revised September 22, 2022 – Revised Step 2 in Correction section.
Revised November 03, 2023 – Added 2023 to Model Year and Added Service Procedure
information.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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