2026 GMC Sierra 1500

I purchased this new full-size heavy-duty pickup, and at purchase the selling dealer installed a 3-inch suspension lift kit with 37-inch tires on 22-inch wheels as a paid dealer upfit. The lift kit manufacturer publishes a maximum tire size of 35 inches on a 20-inch wheel for this kit; the tires and wheels the dealer installed exceed that spec. The lift manufacturer confirmed directly that they would never approve exceeding the 35-inch tire / 20-inch wheel recommendation. The dealer's assistant manager confirmed that NO calibrations of any kind were performed after the lift and 37-inch tires were installed, and said nothing is recalibrated when a lift is done with 37-inch tires. This vehicle is factory-equipped with forward collision alert, automatic emergency braking, front pedestrian braking, lane departure warning, and automatic high-beam control. These crash-avoidance systems rely on forward-facing camera and sensor aim, which depends on ride height and suspension geometry. A 3-inch lift with 37-inch tires materially changes that geometry. With no calibration performed, there is no assurance these safety systems are aimed or functioning to spec. The truck was also never aligned after the lift and the tires are cupping. The headlights were never re-aimed for the higher ride height, and the speedometer was never recalibrated and reads inaccurately. The oversized tires also contact the body. The left front tire has torn into the front fender, the fender well is misaligned, and it is forcing the lower front edge of the driver's door out of alignment. The dealer's only proposed remedy is to keep cutting the fender wells; the trimming already done has exposed electrical wiring behind the wheel well to mud, water, and road debris. I am reporting this because the assistant manager's statement suggests it may be the dealer's standing practice—other customers may be driving lifted trucks with uncalibrated crash-avoidance systems without knowing it.

I bought my 2026 GMC in April. Several times the audio doesn't work work. When this happens audio related safety technology is affected too including turn signal sounds and back camera audio also. A person walking behind the truck can be seen on the screen but no warning beeps are heard. When backing up the warning for getting too close to an object also doesn't work. I called the dealer in early May and was told that this was a known issue and that it needed a software update. took the truck to the dealer on May 8th and the software update was performed. When the update had been completed when I started the truck after the update there was no audio. I told the service advisor it was currently happening and she took it back to the technician. They disconnected the battery cables to reset the system and told me to do that in the future until the issue is resolved. I opened Case #100978480 with GM on June 1st because I wanted to be sure that GM was also informed of the issue. I was hoping they would be proactive and report back to me what they were doing to resolve this issue. Instead I was told that I need to call the dealer and the dealer would call GM because an update might be available but dealers wouldn't be informed and wouldn't check unless I called.