 I recently towed a tandem axle and the rear end of the truck is on the ground. The vehicle is always taching up to the red line. I only have 3000 miles on this truck. The window sticker says that it can tow 6500 lbs and I had my trailer weighed and it was only 5000 pounds. I called them and they blew me off.  They need to improve the rear suspension to allow it to tow better. I also have the TRD package and that does not help. It is only getting 7.25 miles to a gallon towing this trailer.