Hi guys I have a 2000 F-150 XL V6 4.2L 2wd 5-speed MANUAL trans. I have a 7 in Fabtech lift with 35" BFG Mud Ter on 16x8 rims with 4.56 gears. I've gone through 2 sets of 4.56 gears and sick of it. I want to take off the upper control arms, springs, shocks, and rear lift blocks and stick with only the 3.5" spindles in front. I picked up a used stock 3.08 differential and want to drop the tire size. Will I be able to run 285/75/16's with the stock gears without having them blow-out? I'm not going to be doing any more hard offroading. I mostly use it now for hauling my band's trailer. Please let me know if you guys can help. Thanks.

 

A 3.08 is pretty low for 33's. I would go at least 3.55 in your case.

 

3.08 is gonna suck with those tires. i believe that tire is almost a 33 and mine struggled with 3.31's. are you putting the 4.56's in yourself? if your not gonna beat on it anymore then you shouldnt have problems with the gears if they are installed correctly

 

The first set of 4.56's I installed myself and blew out after 10k so I thought maybe I messed up on the install. So I got them professionally done and they blew out after 10k. If the 285/75/16 won't work with the 3.08 can I fit a 275/70/16 on a 16x8? Would I have less probs with that?

 

you would have less problems as far as power loss, but you probably wont like how they look since your gonna keep part of your lift on. those tires are 31's and will probably look a little out of place. I dont see why you are going through gears like that. i installed gears in my friends mustang and he has put over 20,000 really hard miles and no probs. (goes to dragstrip every week and daily driver) the size of the gears shouldnt make them wear any quicker than a factory set that lasts over 100,000 mi easily.

 

Yeah I still have the stock gears from the truck sitting at home but after my luck with getting gears installed I just picked up another rear end that hasn't been tampered with. I got the replacement differential for cheaper than what the shop wanted to charge me to reinstall the gears.

 

you can go with the 33's but for better mileage and overall performance the 31's would be better. whatever you do think it out alot first since you have already blown so much cash on it. you dont want to have to regear or change tire sizes again. i felt the same way you do when i put my 33's on and then found out i had crappy gears after the fact. good luck

 

Yeah, you shouldn't be going through gears like that. Now, I'm no expert and am not nearly capable of installing a set of gears but I've always read if they are not set up perfectly, they will wear out quickly. It really sounds like a setup problem or a defect with the gears themselves.

 

I currently have 285/75/16 with stock 3.55 gears. I do not like the power loss and I plan to downsize to 265/75/16 when these tires wear out. They do look very good though...

BTW: my 94 Bronco had 4.56 gears and 33x12.50 tires. It was a great setup, I think that is the ideal gear for that size tire. I had no problems whatsoever. They lasted way over 100,000 miles...