Hey guys I've searched a ton, read even more, and just need a few simple real world answers/reccomendations. I'm planning on getting a slightly larger tire 265/75/16, to replace my bald 265/70/16 tires on my 98 4runner SR5 4x4. Is this going to jack up my transmission over time, and do I need new optimized gearing for such a slight change? I want a little larger tire/more aggressive, but I don't want to start shelling out thousands of dollars on an older, yet very strong still, truck. Thanks for your feedback!

 

it well be fine

 

You are talking about going from a 31" tire to a 32" tire. It will be noticeable, but not worth doing anything about.

 

Thanks guys, that's what I thought, but just wanted to make sure!

 

I would not worry about transmission at all, it will be fine.

But here is my experience with tires:
I also tried to go to 265/75R16 3 years ago. I have 1996 4Runner 3.4L 4x4 Auto with 4:10 rear.
I went to 265/75R16 size and after about 6 weeks I went back to original 265/70R16 (I have “Revo” now). The main reason was that, with that change, my gas mileage went from 18.5 average to 15.5 average (after recalculating based on the tire size change).
I also felt “loss” of power but it wasn’t much.
Here are the things I have learned in the process of choosing and changing tires.
265/70R16 are P rated tire (P for passenger) it means they have softer side walls (lighter tires) but harder rubber compound on the surface of the tire so they have less rolling resistance than LT tires.
265/75R16 are LT (light trucks) tires, at least that was the only choice 3 years ago, they have stronger side walls (heavier tires) and softer rubber compound on the surface of the tire and that means higher than “P” tires rolling resistance.
To summarize: with that small change of tire size your biggest enemy is rolling resistance. I am sure if you can find 265/75 in a “P” rated tires you will be a lot more happier but as you can see a lot of people have 265/75 and they are fine (if they do not care about gas mileage).
Also if your 4Runer have 4:30 in the rear you will not fill that change as much as I did.

I hope that helps, good luck to you.