[Jackpine]

Originally Posted by hampsterzone

I have been getting mixed opinions from others outside of this forum. Does anyone have 35" tires and 4.56 gears that can give actual hands on feedback? What I wanna know is how much better is your truck off the line, towing, fuel economy, top end power and rpms. According to Offroaders.com I am one the green zone with my tires size and gears that be installed Wednesday. Others say that I will have no top end spend and when I am going 75 mph, I will be super high in rpms and get way bad fuel mileage. Please help with your experience. Thanks a million....... u

Gearing is tricky and you MIGHT be "overgeared" at 4.56 with 35" tires. Bill has explained to me that Ford implemented a torque reduction strategy that comes into play when the PCM senses a reduced engine load. That gear and tire combination MAY reduce the engine load too much.

My truck came with 32" tires (275/65R18) and 3.73 gears. If I increased the tire size to 35", I could get the "stock, effective" gear ratio back by increasing the gears to 4.07 (4.10 is the "standard" size).

However, if the truck had come with 4.56 gears in the first place, they would give me an effective ratio of 4.16 with the larger tires, which probably means you would see an increase of about 200-300 rpm at 76 mph. This is not excessive and certainly should not get you into the "reduced torque" situation.

So, my gut feeling (worth exactly what you are paying me for it) is that you'll be fine with 4.56 gears, but it would be helpful to know your OEM tire and gear values. Bill would be a better judge too.

- Jack