Power loss from tire size

I know this has been hashed and rehashed… The question I have, the loss of power caused by any tire size larger than stock. I remember reading somewhere on the forum that Keith, @dirtydeeds saw something like 40 hp loss from a tire even 33 inches tall. Is this something the ECU does when MPH doesn’t line up with mapping? Like a derate. And if so, any way to get around this other than gearing?

I drive a 2021, so not many after market tuning options, at least that I have found.

 

No. The loss of HP isn't at the crank. It is not a change in how it runs. It is the loss at the wheels because of ratio change. Regearing is the solution.

 

You are remembering correctly as I understood it and it is a separate issue from re-gearing.

I suspect Yellobox could fix it but none of the options are plug and play. I don't want to hack up my cables to find out it doesn't work and the vendor couldn't verify it would definitively work.

For reference Kieth was commenting on a post that had Vivid's supercharged Tundra on 38s; it was this video:
https://youtu.be/qILyFoGgH6k?si=BPIt6MV6DK7tt7JT

 

When you start calculating rotating mass and all from increased weight as well as diameter, it will result in loss of power.
temporary (typically turned permanent) fix is using your tow/haul button.
otherwise, tune/regear will eliminate it. all depends on your ultimate goal and/or budget

 

I’m not disputing power loss is surely a thing from larger and heavier tires, but I will say I watched this video of dragy testing on a tundra and I have to say I was surprised at the results. It is possible the density altitude was different between the 2 days he was doing 1/4 mile testing. I myself am going for a lighter setup as we speak, I just bought tires that are 10 lbs lighter per tire than my current set.
https://m.youtube.com/watch?v=zXQvhh82e30&pp=ygUdUG93ZXIgbG9zcyBmcm9tIGhlYXZpZXIgdGlyZXM=

 

Interesting

 

It’s just hard for me to wrap my head around a 12% loss of power caused by a 3% change in final gearing?

And I really don’t want to go down that whole rabbit hole of regearing, speedo error, top speed reduction etc. just for my vanity of wanting the larger tire “look”. I don’t off road so really no other reason for larger tires, especially if they cause a loss of performance.

 

Then stay stock size. Adding larger tires will reduce performance, throw off the speedo (and the odometer by proxy), and if you are not willing to pay that price for the look I wouldn't do it. When it comes to modding a truck the saying "you have to pay to play" applies to more than just dollars for the mods.

 

How tall is the factory tire? I have 33” tires now and I didn’t notice much of a change in MPG. It was anywhere from 11.5-12.3 before and now it’s mostly around 11.6 so maybe 3/4 of an mpg or so. It seems excessive that it would create such a large HP disparity in comparison to MPG disparity.

 

This post explains the flat loss he was talking about:
https://www.tundras.com/threads/37s-with-stock-gears.14100/page-5#post-3156099
"On top of all of this, the ecu sees the higher throttle position and pulls timing while adding fuel. This causes an actual loss of power to compound all of the above."
and here:
https://www.tundras.com/threads/thoughts-on-4-88-vs-5-29-longevity.119261/page-2#post-3081991
"You need to stop looking at charts Ginny real life. The charts don’t take into account the way your ecu reacts to the wheel speed being slower in relation to the throttle position. The extra load of the bigger tires causes your ecu to pull timing and add fuel. This equates to a 40hp loss. That’s not from the tires. The chart won’t help with that LOL.

when experts give advice it’s not for kicks and giggles."

 

Huh. I guess I stand corrected! I'm certainly not dumb enough (or smart enough) to try and argue with Keith!

 

@Saltyhero13 ...thanks that is the thread I was talking about, have been trying to find that to re-read. I started the thread to convince myself I could live with the loss of power for the larger tire, but only if I had some option to over come those loses down the road.... and SC is not in my future LOL.

 

Weight and diameter are still issues though. This one is pretty obscure. I only remember it because of how ridiculous (for my tastes) the Vivid build was on the 38s. I still can't find that specific post.

 

Like I said I think the Yellow box can fix it I just don't have the time nor the patience to mess with it.
https://www.yellr.com/

I know it is a good product but my conversation with the customer service rep left me with low confidence.

To my knowledge Tundra uses two wire:

 

If they didn't like what was being said they may have blocked the post. Yootoob let's crybabies block posts they don't like. I've pointed out lies and omissions of factual data and the video poster has blocked my comments before. They don't have anything like the community notes on twitbox to call out BS.

 

I will add, from my personal experience, tire weight has a greater effect on perceived power loss vs tire height.

I went from 33inch heavier tires to 35 inch, yet lighter tires by about 5 lbs vs the 33s and saw much better day to day driving performance and also picked up 1MPG

 

My choice of words confused the issue. The first I heard about the power loss was when Keith/@dirtydeeds made a comment about the YT video not on the video itself.

 

Bigger tires and power loss is real; saying for a friend.

 

and here I am trying to research smaller, yet wider, tires to simulate a 5.29 gearing....

I need a NASCAR looking setup.

 

@nobodyintexas .....Lol thought I was the only one looking that way .. some would say smaller tire is blasphemy, I like "real" performance. Part of the reason I ordered the 8" cat back from @dirtydeeds, and didn't just hack off the muffler for something louder.

 

I wonder if a smaller tire would confuse the ECU in a detrimental way?

 

if the Toyota engineers read this forum I’m absolutely sure they wouldn’t have built in logic for smaller tires.

Therefore it’s safe to assume that The truck would go all y2k if you put smaller tires on it.

 

I've heard Mike Sweers himself frequents the forums.

 

Is it bad that I read that as “Bigfoot frequents my backyard.”

 

I would say I "Sweer" resemblance.

 

My SR5 had the OEM 18” steelies and I went down to 17” but bumped the profile on my 255s up to 75 which left me with the same overall diameter of 32.1”. The Method 314s weigh about 11 pounds less than the steelies and the tires I chose are only 1 pound more than OEM.
I must have gained 45 hp by reducing my rotating mass while maintaining diameter!!

 

Rotational mass is a bitch

 

I was looking at 39s lol