With an Automatic trans, I would definitely go with 4:88 over 4:56.
Mine is manual wit 35s. I went with 4:88 and am very happy. The engine is revving about 3000 at 70 mph.


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Just a thought before you go down the gearing rabbit hole, what is the condition of your spark plugs and is your transmission cable that is attached to the throttle body adjusted properly?

My 99 had issues initially when I bought it also. In fact I bought it cheap because it didn’t run well. Wouldn’t maintain gear going down the road and just struggle the high speed. The throttle cable wasn’t adjusted right, and the throttle only opened about 70%. The the trans cable was wrongly set. And the plugs were worn to about 3 times the gap they needed to be.

After I addressed those, 80 mph was a breeze. Make sure your at least 38 psi if on load E tires as that makes a huge difference on the interstate for me. I have a new set of load C Generals to try out here soon to see if that improves the situation.

You use your 4runner like I do. Not a daily, but it see lots of miles and action when we go. I’m on 265/75 E’s and 4.30’s running valvoline max life trans fluid. Not a speed demon, but certainly adequate. If it’s been a while since ATF change, drain that out to and refill. It’s surprising what fresh ATF does.

Also, don’t be scared to lock out that overdrive when needed. Sometimes climbing it’s just mandatory.

I know everyone hates downshifting, but it’s just part of life. You don’t notice it as much in newer cars for lots of reasons, but it’s still there.

Even my 1 ton Cummins diesel manual requires downshifting sometimes, and that thing is the no downshifting king.

Just out of curiosity @, you mentioned 285’s, what tires and load rating you running?

This right here. My truck pulls fine on the hilly backroads with OD off. I didn't notice any drop in MPG as it keeps a consistent RPM instead of constantly hunting for the sweet spot.

I only have to turn OD off when I'm loaded for camping. I recently upgrade to 4.30's with 265/70/16's, so I added about an inch of tire height over my old setup. The change is barely noticeable with the 4.30's. Definitely would be worth it to go to 4.88 if i was going up to a 33-35 inch tire.

I think a 6 speed auto would be the sweet spot rather than the 4 speed autos we have. Technology wasn't around for that back then, but it sure would have been nice to have a lower first gear ratio, 2 overdrives, and a much wider gear ratio spread.

First off, howdy neighbor! (I live in Fair Oaks)

Yeah, that's good advice about being careful regarding the 5-speed vs automatic. I think some of my early concerns about 4.88 came from old posts that were talking about 5-speeds and/or 4 cylinder motors. That's part of the reason I started a new thread: to try to get input specific for my vehicle/usage.

I think you're right about the stock gearing and almost wonder if the drivetrain was dialed in based on the base 28" wheel size even though most 3rd gens seems to have been sold with the 31" option. Or maybe it was done that way to help it score a little better fuel efficiency for the window sticker.

Wow, 5.29 on stock tires! That's going to be pretty aggressive. I assume you won't be using your 4Runner much on the freeway?

Yeah, I guess you're right that the 33" tires combined with 4.88 gears is pretty close to the stock 31" tires with 4.30 gears. Compared to that stock setup, the 4.88 would be roughly 125 RPMs higher at 65mph (2300rpm) and the 4.56 would actually have run 25 RPMs lower (2154rpm).

Thanks for the excellent advice! I'm friends with the prior owner and we've both kept up with the maintenance so I assume it's running well. Plus, it only has 140k miles and the smog tests always come back super clean (the techs are usually surprised how clean) so I suspect that's another good sign about the state of the motor. However, I don't know that anyone has ever looked at the throttle cable so that might be worth checking out.

A big part of the reason for re-gearing is that I want to put lockers on the front and rear so it makes sense to do it all at once.

Regarding the tire pressure, I'm running Duratec 285/75R/16 which are LT rated and I'm not 100% sure what psi I should be running. The tire store put them at 35psi and that seems to be in the ballpark for what other people are doing based on some google searches.

Another good point. Maybe it's just unrealistic for me to expect a heavy truck to accelerate uphill in overdrive. It just currently feels like I'm stuck in 4th with no power unless I floor the gas pedal to get it to drop into 3rd at which point it jumps 800rpm and starts moving. It'd be nice if I could get away from those Jekyll/Hyde extremes.

I ALWAYS recommend that people with larger than OEM tires or higher capacity rated tires (LT or load range D/E/F) chalk test their tires to find the best psi for full engagement across the tread blocks. I've had customers complain of a rough ride in their light duty trucks (1500) that are running load range E tires at 80 psi. At that pressure with such little weight you will feel every crack in the road and have a terrible and small contact patch.

THANK YOU! I was really hoping to hear from some people who have the same drivetrain and had upgraded to either gear size.

Personally speaking, I'm not too worried about it being "quick around town" but its very interesting to hear that you're still dropping out of OD to climb long hills. I wonder if the extra 140-160rpms that the 4.88 gears would give at freeway speeds would allow you to stay in OD? If not, that might push me a bit closer to the 4.56 gears. My reasoning is that if I'm going to be running in 3rd gear the whole way up the mountain either way, I'd rather do it at 2800-3300rpm than 3000-3500rpm

That sounds like a really good idea. I suppose I should probably do the test unloaded as well as fully loaded to get appropriate pressures for each scenario?

It would probably be a good idea if your cargo or trailer tongue weight is a couple hundred pounds or more.

Actually I'm wrong. I did my calculations off stock 15s. 4.88s would give you 4.55s on 285s. 4.56 would be a 4.25.

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