Gear Ratio calculator

We all know that gear ratio calculators are readily available in a chart form, but I just stumbled across this one. It'll quickly show you the final (.58:1 6th gear) RPM at any speed, with the tire height and gear ratio you enter.

https://www.nitro-gear.com/Articles.asp?ID=259


I used it to quickly show the actual differences between stock tires /gears and my larger tires /lower gears. Pretty cool.

Going from 32" tires and 4.30 gears to 34" tires with 5.29s, my rpms will increase by:
60 MPH - +248 RPM
65 MPH - +269 RPM
70 MPH - +289 RPM
75 MPH - +310 RPM
80 MPH - +331 RPM

FYI, for anyone on the fence between 4.88 and 5.29, this shows that there isn't a giant delta. With 34" tires at 80 MPH, the difference is only 188 RPM... At 60 MPH, its only 141 RPM different.

In my opinion, our trucks are definitely geared too high in original form. Some additional RPM should be a great advantage in just about any aspect of life... Since the majority of my driving is in the 60-70 MPH range, I'm going to love the extra 275-ishRPM rise in engine speed to overcome the added load created by larger tires.

 

4.88s are a waste of space imo. 5.29s all day

 

Ain't that the troof?

It's my thread, so I'm hijacking it...

I get a bit of a chub every time I spot a good buggy, and just skimmed through your build thread. I'll keep my eyes peeled for you at KOH this year. We're headed down next weekend and will be on the lakebed sometime Sunday. I don't race, but we have many friends that do. 4619, 4521, and 4424 are cars that I have helped with over the years, as well as some of the Team Oregon boys for the Shootout. The hope was to pick up another co-driver this year and take my Tundra down for a rally rig, but that isn't panning out. Taking the slow ride /tow rig only...

 

My man! Sadly as usual life got in the way of my pseudo-4400 build racing this year. But I'm codriving for @jberry813 in the UTV race on Thursday in the #813, and then helping running around pits for the #468 4600 on Friday. I'll have the Tundra with a camper and my Can Am, head out a week from tomorrow. There's a thread that @Cruzer made in the california section, not much chat but a few other people going out: https://www.tundras.com/threads/koh-anyone.100617/

 

Gonna hit some trails and when it gets dark I'll be the King of getting Hammered

 

Great info. I’ve been preaching the 5.29’s for a long time. Never made a chart just knew. It’s awesome to see actual numbers back it up!!

 

I've been told that going to 5.29 will effect the top speed on the tundra to about 90mph by a gear installer. I don't think I've over been over that in the first place and don't see any need too. Just wondering if there is any truth to that?? I have a 2020 tundra.

 

Not at all, I can hit 110 all day. It's at about 4000rpm in 6th but it'll do it

 

I thought that sounded funny. Thank you for your input.

 

I have 5.29s in my 2019 Tundra and my top speed was reduced. Wish I could tune it out but then again I never "need" to go over 100. Most I can do is 95 and the computer shuts me down.

 

Thank you for your response. I still think it's worth doing.

 

Same boat as me. I tested it yesterday and it flat out rips up to 95 on the speedometer, which is likely 92-93 on GPS. I’ve got 5.29’s and 275/65-20 (34”) tires. Speedo calibration is close, but I missed my numbers by a RCH. No biggie, as I’ll bump up to 285/65-20 when I replace tires. Should be dang close at that point.


Anyway, right up to 95, and it just stops there. I decided to roll more throttle into it, and it downshifted! Speed remained the same, just in a lower gear.

Dunno if I’ll chase fixing this “problem”, as I don’t need to boogie that hard here in western OR. Pretty rare that I hit 80, to be honest.

 

Pull the speed sensor fuse (ABS1?) and the sky is the limit.

 

Running 35" KO2 tires with 5.29s and I'm 4 MPH faster than my dash readout according to GPS.

 

At what speed? You are not 4 mph off across the board.
Also, the 5.29s do not affect your speedometer accuracy on a Tundra. Since our speedo is read from wheel speed sensors, gear changes don’t make your speedo change.


If you want your speedo to be accurate, you’ll need a calibrator. HyperTech or Rough Country are the two most common. It’ll fix your speedo (if you input the correct tire measurements) but won’t fix the indicated speed for cruise control. For an example, I did not get my tire info perfect when I set up my calibrator. My cruise control speed reads 58 mph. Speedometer reads 62 mph. GPS reads 60.5 mph. My actual (GPS) speed will be closer to indicated (speedometer) after I move up another tire size. Till then, it’s close enough that I’m not worried…

 

Right, bought gears and tires simultaneously. It starts to drift off closer to 55 mph then stays consistently off by 4 MPH through the highway speeds according to my GPS. I've heard mixed results on the hyper tech on later models and had one on my 2012 Tundra. Part of the issue with speed limiting is the RPM increase caused by the gears.

 

I'm on 35s w/5.29s and at about 40 mph the gap gets bigger until I hit 60 and it's a whole 10 mph off. I've got the RC calibrator and I've had to flash it several times to fix discrepancies. Right now I'm about 2-3 mph off so I'll take it.

Note: the DAP tune removed the governor but yeah I don't wanna go that fast anyway

 

So far I'm willing to do the math and save the money, especially if it wont be spot on.

 

Before the calibrator and gear swap I just remembered to go 5 MPH slower than what the speedo said

 

Odd how everyones experience is different with these setups.

 

It can be as spot on as your truck was in original form. Unfortunately, it’s only as accurate as the I formation that we feed it. I made some calculated guesses on tire size and missed it by a hair. I could pull it out and adjust, and it would be dead nuts on.

 

Anyone tow with 5.29 gears? I’m curious what rpm’s are at? if it messes with the torque band at all?

 

I do, and it is glorious.

I’d have to confirm for exact numbers, but the info below will be within 100 RPM.

I tow our 25’ travel trailer a good amount, typically 4,000 miles per year. It weighs as much as 7,200# when loaded for a longer trip.

I tow in S5, and rarely go much over 60-65 when towing. I have 34” (LT275/65-20) tires.

In 5th gear, I’m in the 2,300 rpm range. As soon as I start climbing a grade, I click down to 4th gear, which puts the motor in the 2,900-3,000 rpm range.

After tuning with HP Tuners, my peak torque is at 2,900 rpm. Much lower rpm than it was when stock.

The gears really shine when towing!

 

Seems that there was some chat earlier in this thread about speed limiting. I can help with that.

Factory tuning will govern your speed to something like 106 mph. In 6th gear, I believe that’s about 2,775 rpm. Well, the truck computer doesn’t know you’ve changed gears to 5.29, nor does it know you’ve installed 34” tires. What it does know is that 2,775 rpm in 6th gear is as fast as it’s allowed to go.

With 5.29s and 34s, 2,775 rpm is about 92 mph. That’s your new limit with factory tuning.

With any decent tuner, you can easily adjust the fuel cutoff value to a higher level. Shit, make it 186 mph. You’ll never hit a limiter, other than those of basic physics.

I don’t care about going over 90, but my limiter had to be bumped up for dyno tuning because it would hit it in 4th gear. With my rev limiter bumped up to 6,300 rpm, it would hit just a fuzz over 120mph in 4th on the dyno. Definitely needed the speed limiter adjusted for tuning…

 

I just clicked on the link in the first post and it gives an error. Anyone know the changed address?

 

Maybe it is this one just a different name?

https://nitro-gear.com/rpm_calculator_us

 

Yessir. Looks like the link expired. Thanks for updating!

 

I have 4.30 and getting ready to level the front. Going 285-60-20, looks like I should be very close and not need a Hypertech. Am I off with my thinking?

 

Your speedo will be off, but not a huge amount. Up to you if you are ok with the level of accuracy.

I’d check against a GPS and decide if it’s within your range of GAF.

 

What about 5.29 on 35"? Would that roughly be the same?