2500HD Gear Ratio [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: 2500HD Gear Ratio


curtisb
11-17-2003, 12:06 PM
Hello all, I am getting ready to upgrade my tires on my 2500HD D/A to H2 wheels with BF Goodrich 285/70 R17 AT's and am wondering about the towing ability. I am sure that the sidewalls will be plenty stiff for towing but my concern is the gear ratio.


Has anybody given any thought to or changed the gears in their trucks? I would effectively be going from a 3.73 to 3.46 gear ratio. I am figuring that I am going to purchase the Juice/Attitude combo to offset the loss of power due to the perceived change in gear ratio of going to larger tires. I am pulling an 8K fifth wheel.


Anybody have any thoughts to whether the loss of power will be significant, etc.? Will the Edge Juice at the 40 or 90HP level compensate well?


Thanks.


Curtis

403turbo
11-17-2003, 01:39 PM
Curtisb,





Yes, some have noticed that the D/A will "loose a step" with the taller rubber on. You are correct in thinking that it will make towing more difficult. Most serious haulers either stick to 265's or juice the truck to make up the loss. The Juice will more than make up for the higher gear ratio.





I would suggest seriously looking at an Attitude controller because of the EGT,boost and Tranny slip monitoring ablility. Nice to have when towing

Jeli
11-17-2003, 11:53 PM
My H2/315's are fine empty but my enclosed sled trailer takes the oomph out of it at highway speeds. IMO the Dmax likes to run around 2000 rpm. At 70 I'm at 1700 rpm. It just never gets into the right rpm range especially if you do back roads and drive 55-65. If you do a lot of RVing or get into the mountains 265's would be a better choice regardless of a controller.


I like my BFG's. The 3 ply sidewalls hold a load even at low pressures. I'm running 35 psi but my trailer is only 5K.