I know this topic has been discussed a lot but it sounds like I use my 4Runner a bit differently than most so I was hoping to get some advice specific to my situation.

While my 3.4L automatic 4Runner is not my DD, it does see a lot of it's miles on the freeway while in route to camping and snow/mud wheeling trips (usually 1-3 hours on the freeway each way)

I had 265/75R/16 tires (~31.6") with the stock 4.10 gearing and when fully-loaded with gear on the freeway, I had trouble accelerating (and sometimes even maintaining speed) on hills unless I floored the gas pedal. I have sliders and a roof rack but that's the only other additional weight.

I just upgraded to 285/75R/16 tires (~32.8") and will be doing a re-gear while adding lockers and had planned on going with 4.56 gears. While I don't expect the re-gear to turn my truck into a race car, I had hoped that going with 4.56 gears would at least give me a little extra pep on the freeway while keeping the RPMs at a reasonable level (to help with noise, engine wear and fuel consumption).

However, I've read numerous posts claiming that the upgrade to 4.88 was barely noticeable and should be considered the minimum so now I'm second-guessing my plan to go with 4.56 gears. If anyone who has upgraded to either 4.56 or 4.88 gears could share their thoughts with regard to my application, I would greatly appreciated it.

Oh also, I will not be upgrading the size of my tires in the future and the only other weight-adding upgrade I may do would be a front bumper and I'm not convinced I'll even ever do that upgrade. Thanks

Play with a gear ratio / rpm calculator or work it out yourself to see what rpms you will run with the different configurations.

My opinion is that 4.88’s will do better for you. It’s rare for people to regret going with lower gears. If the higher rpms help you drive a few mph slower on the freeway then you’ve solved the fuel consumption bit.

If your primary concern is more power and off-roading capability then go with the 4.88's. Just keep in mind that you will be turning over 3000 rpm's at 70mph, not very pleasant on 3 hour drives.

Thanks for the reply! Yes, I have been playing with a calculator but I thought it might help to hear some real-world impressions from people who have first-hand experience.

As far as driving slower, unfortunately that won't work since I usually head up with some friends who all drive more powerful trucks so I have to keep up lol.

Oh dang, I've been using this calculator and it's showing 2,482 RPM at 70 mph. I wonder if I've entered something wrong?

Gear Ratio Calculator

1st Gear 2.80
2nd Gear 1.53
3rd Gear 1.00
4th Gear 0.71

Axle gear ratio 4.88

Tire size 285/75R/16

What is your current rpm at 70mph?

I like to start there and then multiply the ratios of the new tires and gears.

Thanks for the suggestion! I took my 4Runner out on the freeway and 70mph (on the GPS app) currently puts me at 2100rpm which is what that online calculator estimated based on my current gearing/tires. Thus, I think its reasonable to assume the calculator is accurate and it gives me the following rpm for each gear ratio:

4.56
60mph -> 1988
70mph -> 2319
80mph -> 2651

4.88
60mph -> 2128
70mph -> 2482
80mph -> 2837

Those 4.88 revs don’t look too high to me. 200rpm jump at cruising speed in exchange for more useable power and less strain on the entire drivetrain.

Yeah, compared to my prior setup before I got my latest tires, I'd be looking at +270rpm at 60mph and +320rpm at 70mph with the 4.88 gearing. If I went with 4.56 then I'd be looking at +130rpm at 60mph and +160rpm at 70mph.

That's a good point about reducing strain on the drivetrain but wouldn't +270-320rpm for a majority of the vehicle's miles be increasing wear on everything before the gears? (ie the motor and other related components)

No, the motors really don't mind revving at all. My 3RZ is geared such that it runs 3000 rpm at about 75mph. Oil analysis confirms that it is wearing extremely well.

Most of the mpg loss will be from the bigger tires. Remember too that your overall rotating mass and drag will be increasing so it's better to be geared lower than the factory setting for that reason.

Since we have different engines, can we really use your motor's long term performance at higher RPMs to predict how a V6 motor will fair under similar circumstances? I know that both are extremely reliable but I was under the impression that 4 cylinder engines are typically designed with higher RPMs in mind since that is where they make their power.

However, I was doing a bit more reading and ran across something that supports the idea that the V6 doesn't mind higher revs. The base tire size for the 3.4L was 225/75r15 (28.3") and if you compare the RPMs of that stock setup to one with 4.88 gears and 33" tires, they are almost identical:

28.3" tires/4.10 gears
70mph -> 2,420

32.8" tires/4.88 gears
70mph -> 2,480

In other words, running at those higher RPMs long-term should be fine since I doubt Toyota would sell a base configuration that risked long-term reliability.

Both engines have the same valve train setup. I bet the 5VZ actually has a higher bore-to-stroke ratio than the 3RZ, meaning it would actually have lower cylinder wall velocity at the same RPM.

A stock automatic 4Runner with 265/70/R16 tires has too tall of gears to begin with. It constantly wants to lug around in sub-2K RPM. The only reason why is that you can eek out a tiny, and I mean tiny, big more miles per gallon that way. I would argue that a stock auto should have come with 4.56 gears like some of the 2nd Gen 4Runners and 1st Gen pickups did. Also, the 5-speed and autos have very different transmission gear ratios so be careful comparing the two. The grimjeeper website mentioned above is very accurate and has the correct ratios.

Just remember, this is the 5VZ-FE engine we are talking about. It's not perfect by any means but one thing it is is overbuilt and very durable. Cruising at 2100 RPM or 2500 RPM isn't going to make much of a difference, if at all to the life of the engine. I am hopefully going to be putting 5.29 gears in my 4Runner with stock tires by the end of the year and will be cruising at 70 MPH at 2900 RPM.

I've had 4.56s and 285s for a couple years now and I still feel conflicted about my choice.

I spend a lot of time on the interstate too, which is why I chose 4.56s over 4.88s. I find myself dropping out of OD frequently to climb long hills. It's not as quick around town as it would be if it had 4.88s.

It also turns ~2500rpm at 75mph and gets close to 19mpg on the highway. I dunno. Really these things need 4.88s and a 5 speed w/ OD, not this goofy ass three speed transmission.

4.88s would give you an effective ratio in the 4.30s. I'd do it.