Hey guys! For my first thread I just wanted to share some resources I've found super helpful in researching this "What gear ratio should I run for X setup?" topic.

There's a few variables to be considered here:

• What transmission do you have?
  This link can be used to find all the technical specs of your 4Runner (or other car/truck) including the gear ratio of each gear in your transmission!
  1999 Toyota 4Runner Technical Specifications - DriverSide.com

• Whats your differential's gear ratio?

• What tire size will you be running?

• ...and of course, How do you plan on using the vehicle? A driver who has a vehicle that sees mostly freeway miles is most likely going to want a very different final drive ratio than someone with a dedicated crawler.

These are (what i understand to be) the basics of answering "What gears should I run", so we won't be getting into things like double T cases or crawl boxes.

Let's take a 255/85r16 (33.1") tires on an automatic 3rd gen T4R with 4.10 gears...
Using the link from the first bullet, we can fill in the information on a gear ratio calculator to find out what driving this vehicle could be like by visiting a gear ratio calculator like this one =>Gear Ratio Calculator
In the first attachment you can see that at 70mph the engine will be running at about 2054rpm. At this rate, any slight elevation or need to accelerate will most likely downshift or bog if it doesn't. It also implies that although it's comfortable at 70mph on flat ground, it probably took quite a bit longer to get there as this gearing loses a lot of torque.

Now let's take that same T4R and regear it to 5.29. You can see the results in the second attachment. Notice that at 70mph the engine will be running at 2651rpm. At this rate, you should have more available torque for climbing hills and passing without downshifting as much. A drawback here is that 2651rpm is quite a bit noisier than 2054rpm, which could get annoying on longer highway drives. It also implies that although relatively high revving on the freeway, it will have an easier time accelerating and hauling heavy loads like armor, steel bumpers, gear, or towing. You also have the option of bumping up your tires to 35's which will again trade off some torque but bring the cruising revs down.

This time, lets regear the same T4R to 4.88. These results are in the 3rd attachment. At 70mph the engine is at 2445.5rpm.

Finally, lets check out the same T4R with 4.56. These results are in the 4th attachment. At 70mph the engine is at 2285.4rpm.


TL;DR

• IMHO, for this 3rd gen auto 4Runner on 33.1" tires, 4.88 seems like the happy medium in terms of available torque and cruising rpm.

• If you mostly drive big elevation changes, offroad, and/or want the option to eventually get 35's, you might lean more towards 5.29

• If you mostly do long highway drives and/or don't ever plan on going to 35's, you may be happier with 4.56.

Attached Images

       

What engine do you have in the 3rd gen? 4.88 with 33s seems insane to me but I guess if you dont have to drive it much on the highway, it wouldn't be terrible... I've got 4.56 with 35s but I have the V8 and I honestly wish I had 4.10s for more wheel speed and lower highway rpms. 33s were just fine for me with the stock 3.73s.

This 3rd gen is a 3.4L v6. Which has like 90ft/lb less torque than your v8. its transmission has very different gearing as well, not to mention lacking the 5th gear yours has. An extra gear means your other gears can be closer together so a longer (numerically lower) final drive won't rob as much torque.

Cruising 70mph at ~2200rpm in a v8 is going to be a very different experience than in a v6. Plus if you have to drop a gear, the next lowest gear is much closer vs in a 4-speed dropping a gear sometimes puts you way too high in rpm.