26” wheels with V6 drivetrain

[DJ Morpheus]

Hello all. I own an 18 Silverado 1500 LT , double cab, 6’6” box, 6 spd transmission, I have opted to put 26” status alloy empire wheels with tire size of 305/26/30. Stock transmission gave out. Stock  Transmission went out. They said torque converter and pump went out then everything else went with it. Was able to replace the entire unit with a remanufactured from GM. 1 month later, back to the shop (dealer). They covered the repairs because it was under warranty but if it goes out again they won’t because they believe it is the rims causing the trouble. However they will cover if it goes out with stock wheels. Which I will be putting back on. Has anyone else experienced issues with this type of truck and 26” wheels? I did research the “Unsprung weight” makes some sense, however only the transmission gave out, not my drive shaft, drive shaft knuckles, diff, just the goofy transmission which I know the 8 speed has had their share of ongoing things. How is it that a truck that is capable of towing 9k lbs has issues with no load on 26” rims. Pulling a payload in the bed of the truck and pulling a trailer should still have the same effect. If I can’t tow anything with the truck, then what is the point of a truck. I have went back to stock rims to see what would happen. Anyone with info ,thought , something sketched on a cocktail napkin would be greatly appreciated. I do thank you all for your time on this. I have attached the service ticket to this post. 

[Salsa De Piña]

Two or four wheel drive? Two wheel drives came with 3.23 gears and your obnoxious wheels reduces that to an effective 2.83 rear end.  Yeah, I'd imagine your torque converter is working overtime and building up a lot of heat.  A four wheel drive had 3.42 gears, but again, the ridiculous wheels makes that an effective 2.99 rear end.  I'm also guessing you didn't reprogram anything, so the transmission is making its decisions based on inaccurate speed info.

 

TL:DR - They're probably right to deny the claim under warranty.

 

Oh, and your V6 isn't rated to pull 9,000 lbs.  Either 5,600 lbs (2wd) or 7,100 lbs (4wd).

Edited February 26, 2021 by Salsa De Piña

[DJ Morpheus]

Thank you for your reply and wisdom on this. It is a 2wd. I did not reprogram. Just thew them on. Claim was not denied. But moving forward of it going out again, then I’m SOL. So to avoid that, I went back to stock, so I will still have the warranty as long as it’s all oem. 

[sharkeysierra]

Plus, the added weight of the wheels and tires, 30” lifts it higher, messes more with the aerodynamics (I know the truck already doesn’t have aero). The V6 already has enough of an issue trying to move the heavy weight of the extended cab truck around, stock. 
 

You need torque to break the driveshaft/axle shaft or gears.. yeah the V6 doesn’t have that. 

[WHITESSTOWPIG]

Towing capacity is based off the gear ratio, tire diameter, and the weight of the truck.When you add larger wheels without regearing the differential to match you mess with the final drive ratio which throws the speedometer out of sync and messes with all the shift points in the transmission.A mere 10lbs in wheel added weight can feel like 300lbs in payload and 26's probably add additional 40 lbs in wheel weight on each corner.All of this combined can make a transmission feel like your pulling 14,000 lbs when your really only pulling 9,000 lbs.The V6 models also do not have transmission coolers and that is another reason the towing capacity is lower.To summarize larger wheels cut down on your towing capacity and the life of your transmission no matter which way you cut it.If you keep them I would at the very least regear the differential to match and add a transmission cooler to the truck