Do I need to regear?

[robandkat]

I am running 33.7 inch BFG tires (305/65/18) and I am towing a two horse trailer. I have on order an 87 custom tow tune, is this enough with 3.73 gears or do I need to change? The truck is a 2006 f-150 5.4l 4x4 super crew with an automatic trans. The truck is used for city and highway driving, and towing. If I need to change should I go with 4.10 or 4.56 gears.
Thanks

[88Racing]

I think with the 33's your real gear would be like 3.55-3.60. not to shabby of a gear range to have but not the best to pull heavy loads with or to go serious off roading with.
The 4.10 would get you back to the real feel of the 3.73's. The 4.56 would be a little much but would be there if you wanted to lift the truck and put 35's on as meats.
The expense of having to change them would be 900-1500 so I don't know if you would think this would be cost effective?

Lars

[408F150]

How much does the trailer weigh? Under 6,000# and you're okay, if more than that or if you're in extremely steep country you'd need to regear to keep the transmission happy.

[JWBFX4]

Me personally....I would not regear with that size. Just because I dont feel that the 4.10's are that big of a jump for the price, and 4.56 would be a little much.

[Jackpine]

The trailer's probably in the 3000-5000# range depending on whether it's holding one or two horses.

We talked about this in another thread, and 3.90 gears (which probably don't exist) would give him the same effective gear ratio as stock. 4.10 gears would be plenty big enough.

But, he'd need to replace both the rear and front set - pretty expensive. I don't think I'd do it unless I saw that the transmission was really having trouble. However, I'd sure get a customized tow tune for the actual load pulled.

- Jack

[robandkat]

Thanks for all the responses. The trailer is about 4000 pounds empty, each horse is about 1000 pounds, plus riding and misc. gear. So I am guessing the total will be around 7000 pounds. I also have on order a custom 87 tow tune. I have been told that if I do change gears that I should go with 4.56 gears. I am not sure what is better 4.56 or 4.10 gears with the auto tranny and 33.7 inch tires. If the custom tune is not enough and I change gears after I get the custom tune can I change it in the tuner or do I have to get the custom tune redone?