Is a tune required after 5.29 gears with 35" tires?

Is a tune required after 5.29 gears with 35" tires? I've read conflicting information here on whether or not that is needed.

I've read I really only need it if I'm going to install a SC. Any thoughts?

 

Tune for what? Speedo recalibration? Transmission shifting? Not required but would likely help with performance.

 

I guess all of the above? Also, I've read there is some limit to max driving speed on 5.29 and that could be removed after a tune. Is that true?

 

You can get this for the speedometer. It just plugs in, but behind the gauge cluster so it’ll take some disassembling of the dash to get to. It’s removable so trace is left behind.

https://hypertech.com/pages/speedometer-calibrator

I think 5.29 gears limit top speed by the way they work, not because of any tune. They just don’t spin enough to get a higher speed, but it’s probably still over 100 so not really what you want to do on 35s anyway.

 

There’s a speed limiter on most modern vehicles that corresponds to the tire rating that the vehicle is delivered with usually. Going up to 35s changes your final drive ratio down, going up on your rear gear ratio changes it back up. Not sure where that combo lands you and your Speedo, someone with experience there could chime in. But if the truck thinks your going faster than you are, your top speed will be limited to it’s perceived speed, not your actual speed.

 

So a fix to this would be a tune? I just don't want to be limited to 80mph in the event I need to overtake for whatever reason.

 

You’ll have to research what you’re getting in whatever tune you’re interested in. Some tunes only adjust some features. The main goal sounds like Speedo adjustment. Research whether the hypertech is fixing the signal to the computer (which would fix your issue) or just fixing the signal going to the speedometer (may not fix your issue). How far off is your speedometer now?

 

I don’t think it’s required. I don’t remember exactly where, but I have read on here that people with 5.29s/35s can still hit 100mph or very close to it.

 

Found it:

Pretty sure he’s on 285/75r18s like me. It’s a skinny 35…

 

Okay cool. 90+ is plenty. I just wasn't sure if I could achieve that speed with just the gear swap.

 

You don’t need a tune. The truck will drive and shift better than ever before.

Only issue you may run into is banging off rev limiter between first and second if your tires aren’t big enough. A 35 won’t do that.

 

Would a tune help with 35s without a regear? Given that regearing is about 5x more than a tune, that’s something I’ve been considering.

 

From what I've read, the truck seems to hit a limiter at like 97mph (indicated). I never experienced that but was already tuned once I got 5.29s. The main point to bring up the tune is the limiter is disabled. Even with stock 4.30s you are limited to ~106mph, and for whatever reason that seems to drop with the 5.29s. I do not think a speedometer calibrator like posted above will fix the issue because the speedometer reading is separate from the trucks calculated speed---ie the ECU calculates speed based on rpm, where as the dash calculates it (I think) off of wheel speed sensors, so correcting the dash speedo wouldn't affect the actual speed governor in the ECU.

Outside of that speed governor, a tune isn't needed. And if 97mph or whatever reality ends up being is fast enough for you, then you're good to go.

 

This is where my confusion stems from. Hence my question in this thread.

 

I'm running the TRD (Magnusson) supercharger and 5.29 gears, and I'm on 305/70r17 tires, approximately 34" in diameter. I top out at around 106 mph before it hits the limiter. That's better than when I ran 305/55r20 tires, approximately 33" in diameter, where it would hit the limiter at 103 mph. In any case, the limit is high enough for 99% of your driving.

Interestingly, this combo has resulted in the speedo being perfectly aligned to the actual speed.

 

Well I think that's as clear cut of an answer as you'll get, and pvmike's post seems to corroborate what I said. You may have a decreased maximum speed, you may not. Worst case you lose a couple mph of maximum speed, but should still be able to do 100mph (actual speed). If you want to go faster, you'll need a tune to eliminate the speed governor. If the governor that the truck currently has is fine with you, then it'll probably be fine with whatever the max speed the truck allows once you get 5.29s. From a physical limitation, the gears are fine going 120+ so won't be your limiting factor until you modify other things.

 

That's great to know since I am currently running 35.28" tires (305/70/18) and will soon be upgrading to nitro 5.29 gears with a powertrax grip pro LSD in the rear.

 

I run 35x12.50s on 5.29s with stock tuning and am happy.


ETA second gen, 5.7 etc

 

I was so close to pulling the trigger on some Sierra 5.29s and a powertrax last year. Just got super busy, and I still don’t know where I would have them installed.

Is Sierra still what you 5.29-ers would recommend?

And does anyone know of a reputable installer within 4-5hrs of Nashville?

 

If you don't like the shifting or feel like it does not have the power you expect then yes. Tuning technology has come a long way. Honestly your truck, with or without gearing mods, is in the Stone Age compared to what a current Tune will
provide. Night and day. A Tune with your Gear mod, along with compensation for tire diameter size will amaze you. Want the best Tune, service and lifetime support (which includes updated Tunes at no additional cost)? Contact Marc at @MZiggy and YotaWerx Tuning.

 

Tune should be mandatory with 5.29 imo.. In addition to removing/adjusting the speed limiter, the final drive ratio will be corrected for the 5.29 ratio and tire size. Won’t do anything to correct the speedometer, but the engine and transmission will know the actual speed and adjust accordingly. No need for banging off the redline on the 1-2 shift.

 

100% accurate^^^


5.29 with 35’s and stock tune is better than 4.30’s. The difference after adding a good tune was amazing.

In my opinion, a tune is absolutely worth it with 5.29’s.

 

Okay. What kind of tune?

 

It's not "needed" but i would try the tune first, I ran 35's on stock gears for a few years and thought I was fine, until I got it tuned. It woke up the truck, had better throttle response and smoother shifting. Eddie from OTT tuned my truck, and I think he still offers free re-tunes. When I moved up to 37's and 5.29 gears, I met up with him again and he re-tuned no charge.

 

You’ll find mixed reviews and multiple answers for this one. None are necessarily wrong…

For my use, the right tune was custom tailored for my truck using a dyno and HP Tuner. This dialed in the engine part for efficiency and performance, but not much for the transmission. In order to dial that in, I spent a lot of time working with other people in the Tundra community that are more savvy with tuning software. Once I had my head wrapped around the lingo and understood what I was doing, I started making small changes to shift points, TCC control, hysteresis, intake tuning, etc. It took a while. Probably a dozen iterations before I was satisfied with how it all worked, especially when towing my travel trailer. That was the toughest part…

A ton of people are very happy with the tuning options that are available through various retailers, but I wanted the ability to make changes. As far as I know, any of the available tunes that you can purchase are locked and you are unable to modify their proprietary data. Nothing wrong with that, just not my style.

All that said, I’ve never been able to compare my tune to another option.



Back to the whole speedometer deal and limiters…

My understanding is that the OEM speed limiter is governed by a specific rpm in a gear. For example, let’s say 2,600 rpm in 6th gear. With stock gears, tires, and speedo calibration, this is ~106mph.

When we go to bigger tires, the speedo is off. Transmission shifting gets a tad pissy. We fix the speedo with a small inline “calibrator” from HyperTech or Rough Country. All this does is adjust speedo reading. Does absolutely nada for transmission control.

When we regear, the speedo stays just as it was with stock gears. This may sound off to folks that have regeared other vehicles, but it’s true. Tundra reads wheel speed sensors to generate the speedo signal, not t-case output speed like many others do. The wheel speed doesn’t change when we regear, so your speedo is still the same.

But, the transmission and engine control don’t know you’ve made a change yet! With this gearing change, you’re now (in my case with the 34” tires I had) hitting that 2,600 rpm in 6th gear at only 93 mph. That was my new limit with 5.29 gears.


Is that fast enough? Typically, yeah. That’s not the reason to tune though. You want to tune for all the other reasons. Losing the speed limiter is just one of the small bonuses. If you’re using a dyno, you’ll need to disable it (actually you just increase it to an unobtainanle number) because you need to hit redline in 4th gear. That’s faster than the OEM limiter will allow.


Long winded, sorry. A tune is fucking great.

 

Makes sense, thanks. Given that info, I'm left with 3 paths for a tune:

1. A "canned" tune from a 3p vendor.
2. A standalone device such as a HP or Bully Dog where the user tunes it themselves l.
3. A custom tune which includes a Dyno, etc.

My question is, which of these has the most bang for the buck?

 

Bang for the buck, probably a tune from a reputable vendor. You will pay for the credits to unlock your VIN, as well as for their time and tune data. They will use their MPVI, likely either a VF or HP. This should cost $200 for the credits, plus whatever they charge to provide the service.

Bully Dog needs to leave this chat.


You can buy your own HP MPVI for ~$400, credits for $200, and then try to figure it out. It will not come with any tune beyond a stock tune file that you can modify. Remember to aways “Save-As” before you start, so you never lose the start point.

Having it done with a dyno is the most expensive. Believe I paid about $850 for dyno time and tune writing, on top of the credits and MPVI. Took most of the day at a local shop. I could have saved $400 by letting them use their MPVI, but I wanted to be able to tinker later. If you decide to let them provide their MPVI, make sure you get a copy of the tune file on a thumb drive or emailed to you. You paid for that custom work and it should belong to you. Not the case with a canned tune file.

 

For a stock truck I would have OTT or YotaWerx tune it. They work with local shops and send the shop the tune file and they will load it in, that saves you $400 of buying the physical hardware needed to flash the truck. If you don't plan to tweak the tune much that's what I would do.

 

If you’re near Sholo, AZ my tune partner Brody can help you out. Shoot me a PM if you’d like his info. His website is Downhill Dragon Tuning.

 

My truck is in the shop as we speak. I ended up going with the guys over at AZ Toypros in Mesa.

I should get it back tomorrow by end of day. I'll have my initial thoughts then.