I have a 2001 Suburban 4x4 with larger tires, 285 75R16. It also has a 2 in body lift. The speedo is off about 4mph and I know this can be recalibrated, but does anyone know how important is is to change the transmission shifting pattern? Will recalibrating the speedo correct this? I noticed that it has a hard time downshifting, and I'm worries about tranny damage. I've experienced some engine overheating when climbing slowly up a steep hill because I think the engine is working too hard and not downshifting quickly enough, plus I get pinging. I want to avoid using the Tow/Haul mode all the time. Thanks!
