Upgraded from 265s to 275s. lost acceleration and mpg

02SE · Oct 31, 2020

A larger diameter tire takes more power to spin. A more aggressive tread increases rolling resistance. A heavier tire also takes more power to spin. Any lift, even just from the slight height increase of the larger diameter tire hurts aerodynamics.

It all adds up.

Regearing to a lower (higher numerically) axle ratio, can regain some acceleration. But for the slight increase in tire size you have gone with, it's an expensive solution and will never regain the loss in MPG.

I wouldn't consider regearing unless going with a 35" tire and lots of added weight from armor, bumpers, RTT's, etc.

rigtec · Oct 31, 2020

Johncmng said:
Will swapping gear fix this? Can I get the acceleration and mpg back? I went from 18mpg to 15.5mpg. And what does swapping gears? Do I swap the gears in the gear box or swap gears in the rear AND front diffs?

Hi Johncmng,

265 or 275 is the width of the tire in mm (millimeters)! That 'ALONE' won't cause a decrease is acceleration; an increase in tire height will! But the $,$$$.00 you're contemplating to spend seams (IMHO)... counter-productive!

I went from the stock Geolander 245/60 R-20 (on the LE) to a Good*year Eagle LS-2, 275/55 R-20 with only better mpg and an Incredible High speed Banking Stability & performance on highway curves to gain!

The '55' = the sidewall height(%) of the width of the tire, so this tire IS a bit higher than the Factory Yokohama Geolanders, but the nominally increased MPG, and High Speed Banking performance, makes up for any difference in acceleration loss by far!

I say that because, the ring-gear/Pinion swap is a big job, and can be expensive... remember, the front... And the rear differential gears must both be replaced, so if your goal was only to enjoy the benefit of a larger tire on the truck, that small job just changed entirely, ...J/S 'Best to you and yours!

rig, cheers!

JPOVS · Nov 1, 2020

These guys saying you need to have 35’s or even 39” tires in order to regear are wrong. I’m not going to say anything else other than watch this video that Jason did: Flashback - Re-Gearing your 4Runner - Is it worth it? - YouTube

One other note checkout the YouTube video where Nitro Gears did a stock Tacoma with 5.29 gearing. I know it’s a Tacoma and there factory gearing is crap, but what Nitro did is even deeper than what 4Runners do.

02SE · Nov 1, 2020

JPOVS said:
These guys saying you need to have 35’s or even 39” tires in order to regear are wrong.

Well, I said I wouldn't consider regearing unless going with a 35" tire and lots of added weight from armor, bumpers, RTT's, etc.

You or anyone else can do whatever you want with your 4Runner. You can regear a completely stock 4Runner if you want. I think our 4Runner is fine with stock gearing for our needs. If I want to go fast, or tow, I have other vehicles for that.

That doesn't make me or others wrong. It just means we have a difference of opinion.

largefarva · Nov 3, 2020

PriusChat

these guys might have some tips for you, bro.

Jetboy · Nov 3, 2020

JPOVS said:
These guys saying you need to have 35’s or even 39” tires in order to regear are wrong. I’m not going to say anything else other than watch this video that Jason did: Flashback - Re-Gearing your 4Runner - Is it worth it? - YouTube

One other note checkout the YouTube video where Nitro Gears did a stock Tacoma with 5.29 gearing. I know it’s a Tacoma and there factory gearing is crap, but what Nitro did is even deeper than what 4Runners do.

Did you see the video where they raced the 3rd gen Tacoma with 5.29 and stock - and the stock one was faster in a 1/4 mile?

You can regear for small tires. I did. And then undid it. I have both sets. I can swap at any time for little cost. 3.73 works better for daily driving with 33" tires for me. 22% gear ratio change is too far for a 5% tire height change. Or at least it was for me.

TheHolyCannoli · Nov 3, 2020

I went from the stock size Terra Grappler G2's to the Wildpeak AT3W 275/70/17's C Load...lost about 1/2 - 1mpg doing my own calculations on every re-fuel. (Can't trust the on-board cpu calculations with non-OEM size tires)

Have noticed MAYBE a little decrease in acceleration, but it could also be in my head because I've been expecting it. Still, to me the 275 size is worth the 1mpg loss and whatever acceleration differences I might have.

JPOVS · Nov 3, 2020

Saying you guys are wrong came off a bit abrasive, and I apologize for that.

With what I have done I feel the 4.88 has been fantastic. I’m not looking for anything that’s fast off the line, just looking to get it back into its power curve. I’ve seen people on other threads recommend 4.56 for 33’s and with what I have done I don’t understand that, with a trailer or not. I did see a 1 to 1.5 mpg increase after regearing on the computer. I’ve never calculated my MPG because I don’t care.

83Mule · Nov 5, 2020

My 275 BFG A/T with a lift cost me 1 to 1.5 over stock and my 285 C's have made no change to that. You don't need to regear until 34'' and up IMO. With a Pedal Commander I get better MPG and enjoy the response over flooring it and getting Marshmellow on my Boot like stock does!

Upgraded from 265s to 275s. lost acceleration and mpg

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