I have a 95 F150 302 with 3.31 gearing and plan on upping to 31x10.5 my next tire change. I am on the highway a lot and was wondering what gearing would be the best bang for my buck? I feel like on the highway now (especially at higher speeds) the stock tire size and gearing are just awful, especially up hill. Always having to drop out of OD to keep up with traffic (65-75mph). I know that changing the gear ratio to something like 3.73 would raise the engine RPM a bit, but if it is a noticeable difference, I'm willing to sacrifice a mpg. Would 3.73 be a good option to consider? I know gearing is one of the changes that can really wake up these trucks as well. Thanks

 

Even with stock tires 4.10 gears in a truck with a 5L engine is minimum IMHO. If you are going to make a gear change, make it worth the effort. If it were mine....4.56 would be my target gear ratio.

 

My 5.0 truck with a five speed does nominal at highway speeds on 31s. 65 is roughly 2000 rpm with a 3.55 gear. But the manual has a .80 overdrive which is 10 percent higher than the automatics .70. So a 4.10 and 31s would put you right around the same rpms at 65. If you need a little more oomph, a 4.56 would put you in the 2200 rpm area. Still livable at 65.

 

So you guys are suggesting 4.10? I don't tow at all, you don't think it'll be a little too much gearing?

 

4.10 won’t be too much at all for that 302 especially if you plan to use the larger 31” tires. For that combo, I’d do 4.56.

When my ‘94 was still equipped with the stock 302 I had it regeared to 4.10 on stock tires. It did ok, but since I was living in Colorado at the time 4.56 would have been more appropriate. If you’re closer to sea level, my vote is 4.10 for stock tires, and 4.56 for 31.”

Mine runs around 2,500 RPM @ 75mph, stock tires, 4.10.

 

But you already stated: "I feel like on the highway now (especially at higher speeds) the stock tire size and gearing are just awful, especially up hill. Always having to drop out of OD to keep up with traffic (65-75mph)"

If you were keeping stock size tires 4.10 would be the ticket. Now you are going up in size on the tires, you need to seriously consider going up a notch on the gearing as well. Your 5L engine makes torque at higher RPM, similar to a modular engine. You need gears to multiply that available torque or live with dropping out of OD often.

This is not an apples to apples comparison but our old 1997 Mustang GT came from the factory with 2.73 gears and a 5 speed manual transmission. It was always a chore to keep up with traffic without shifting quite a bit. I swapped in 3.73 gears which were a night and day difference in driveability. I gained 2 MPGs in town, lost 1 MPG at highway speeds (70-75 MPH). A full one point change in gearing made a huge difference. In hindsight 4.10 would have been better choice, but I too was concerned about going too far on gearing at that point in my life.

I have owned two 1993 F150 Lightnings. It came from the factory with 4.10 gearing and big tires. Even with the extra HP and TQ of that 5.8L engine I honestly felt like it needed 4.56 or higher gearing. When I had to tow my trailer and Bobcat it was very obvious lower gears would be beneficial.

My 2004 Excursion had a V10 and factory 4.30 gears. It was monster. Perfect setup IMHO.

Never fear the gear

 

3.73's would put you in same rabbit hole your trying to get out of, going uphill shifts out of OD
Gear Ratio Calculator

 

rla2005 pointed out above what I should have included in mine about dropping out of OD. My combo was 3.55 from the factory and like you stated, it dropped out of OD often at highway speeds. The 4.10 corrected most of that, but just barely. The increase in tire size you desire I bet will still drop OD more than you desire with 4.10.

 

I have 31 10.50 on my truck and regeared to 3.73 traction lock a few years ago. I think it is adequate for the 5.0 but still lacking low end power. It basically just compensated for the switch in tires but didn't go beyond that. I used an 8.8 Explorer gear and diff from a salvage 5.0 Explorer. I would rather have 4.10 but will stick with 3.73 since I have plans for eventually doing a 5.8 swap. Having driven a truck with 4.10s I definitely would not want 4.56 in a 5.0 truck that sees a lot of higher speed highway driving unless it had 32 or 33 tires. A 5.0 with 31s and 4.10s should be a good setup.

FYI extra large oversized exhaust makes made low end power on my truck worse and made highway driving a pain with constant downshifts going up hill. I had a huge tail pipe and a straight through muffler which made no power. Stick with normal sized 2.5 piping and no bigger than 2.25 for duals if it is true or SIDO muffler.

 

Thanks for the response, I think i'll end up saving for some 4.10's as I do a lot of highway driving (back home from college, etc). As for exhaust currently, I just had a shop weld in a (I think 2.5?) inch pipe from the first cat back to the stock exit location. Sounds good enough for my ears and isn't crazy loud. Maybe ill invest in a muffler or two when I have enough money for a dual setup out the back.

 

4.10's would give you around 3.73's somewhere around there with those tires