NAWalton00

I'm new to the forum but have been browsing for awhile. I have been debating upgrading my V8 2002 Ford Explorer to a new F-150 Ecoboost Screw 4x4. Mileage is better and well I love the power in that truck! I would be commuting mostly highway with it, easily 90% of the miles at 70mph. To try to get the best fuel economy I have been researching tire size and gear ratio. But I honestly am missing something! My current understanding is the 3.14 will give you the best mileage but when I fill out online calculators they recommend 3.55 with 35" wheels for maximum mileage at 65-70mph. Is this right?

With my driving habits I get 15.6-18.3mph with the explorer and it's rated 13/17. Would it be pretty easy to get 19-21mph out of the F-150 ecoboost Screw 5.6'?

Leadsled124

Im confused. What eco comes on 35" tires? Are you planning to run 35" tires in the future? Because if you do that changes everything. For hwy i would think the 3.14s will get the best milage. You will be cruising at a lower rpm. I would recommend the 3.55 gearing though. Still excellent millage but imo leaves your options open. If you load the truck up with a bunch of weight that 3.14 gearing is going to need to run a gear lower and the gas milage gain would be lost. Plus the 3.55 will be a bit "peppier". If however your going to 35" tires then all mpg is out the window. Go with 4.10s or 3.73s at the least

69428SCJ

I don't believe you can get the 3:15's in a 4X4. The 3:31's are available. If you plan on putting 35's on it you are going to need more gear or have a truck that really doesn't perform very well. 3.73's would be a good choice for mileage with 35's. If you plan on towing much with it in the over 5K range I would get the 4.10's.

RobertEvans

I'm going to assume that you mean you are going to put 35" tires on an ecoboost which is probably the worst thing you could do if you want to focus on MPG....my recommendation is to keep your 2002 and use the money you save for gas

gw1800

^ This...the only thing I'll add is, if you do go 3.73 and 35's, don't exspect 20mpg's.........

NAWalton00

For the 3.55 is there a size recommended? I probably will just go with the stock Ford wheels. For some reason I was thinking the are 35" in diameter. Will there be much mileage difference between 3.31 and 3.55? I may go with the 3.55 as mentioned for the better hauling.

Also, what is a good price for negotiation. Sticker is 47k for what I'm looking. Thanks for your help!!

NAWalton00

Thanks! So it's a trade off between need of use and mpg. I'll do some more research. Would the stock ford tires be the best for mpg?

ajandersen

From what I understand, the smaller the tire, the better MPG's you'll get. Also, 3.31 gear ratio will save 1-2 mpg from 3.55 (from what I read on there, but that might have been comparing 3.31 to 3.73).

69428SCJ

There are not a lot of 3.31 geared trucks around. I never even saw one on the lot in a 4X4. That ratio is not offered with a limited slip rear end. The 3.31 will give you the best mileage, but you will have an open rear end. The 3.55 is your next best option and is available with a LS rear end. The trucks come with roughly 32" tall tire setups regardless of whether you have 18 or 20 inch wheels. If you plan on putting on 35's it will cost you 2-4 mpg on the highway. I drive 60K a year so I stopped with that nonsense about three trucks ago when diesel was 4.50 a gallon.

Leadsled124

Depends on current rebates. Ford was doing $5k off rebates not too long ago. My truck was stickered at $32,xxx and i paid $26,900. That was the sticker before the dealer did the dealer trade. By the time i got my truck they reprinted the window sticker to read $34,xxx. No idea what they added but my price was already set. Just depends on how much the dealer is trying to overprice