4:88.1 from 4:10.1 Why not?

Hi all.

So I am going from stock 30 inch tires with 410 to 32 inch tires with 488.

2.7 2011 4x4

I am pulling a trailer on occasion.

Using this calculator
http://www.grimmjeeper.com/gears.html

It seems at 70 mph I will only see a increase of 300 rpm.

I know there are a ton of threads discussing this.
I read a lot of people saying that the engine will be screaming going down the freeway with tall gears like this.
And from what I have read it seems most people would not recommend the 488 gears on this tire size.
But if the rpm is only increased by 300 at 70 mph, why not?
300 rpm is hardly anything?
Or am I missing something?

 

You'll be ok with the 4 cyl. I'm running 4.88's with 37's and it's just like stock, the speedo is even correct. They will help with acceleration and towing as well.

 

4.56's would be a better choice if you are only going up to 32's tires.

 

Better choice for whom? If he wants more grunt to tow a trailer 4.88's will work great. They aren't that low. Even 5.29's would be streetable, just waste some gas on the highway.

 

That is what I have read before.
But from the calculator, 488 is only a 300 rpm increase at 70 mph.

300 rpm is not much.. Right?
Which is why I don’t see the downside of 488 at this tire size.
Possibly a little bit of gas mileage loss?

Maybe I should be asking if others have seen a huge jump in rpms and my calculations are off.

 

I have 4.88s and ran them with 33s and my rpms at 70mph were 3k. With 35s now its at 2800 at 70mph. My speedo was also off by 14 mph at 70 mph

 

Now that is different than what the calculator is telling me.
I wonder if the calculator is wrong? With 32 tires, at 70mph it says i will be turning 2570.

If you were turning 3k at 70, then I will be turning more, which i do not want.

The calculator says 2279 with stock gearing and tires. (which is what I see in my truck)

Maybe I have punched in the numbers wrong. Can someone else double check me?

Stock. 410 with 245-75 r16
New setup. 488 with 275-70 r17

http://www.grimmjeeper.com/gears.html

 

I think it would perfect. My buddy runs 32's with 5.29's on an older Toyota pick up, and they only place they feel low is on the highway. 4.88's seem like a good compromise, I think.

 

488 is 119% of 410

So basically, with 488 gears, the drive shaft spins 20% further/more than with 410 gears.

That would equal a 20% increase in rpm at any give speed.
So if I run 2250 rpm now. With 488 i will run 20% more rpm. Or 2700 rpm.

Given that I am increasing tire size quite a bit, I could see that the calculator is correct. I think I just answered my own question.
488 it is.

 

All I can tell you is what my tachometer says. 3k isn't that high. I run 80 mph at 3K with the 35s and get 18mpg still. I

 

rpms at 70? Actual from gps if you have them.

 

X2 on this one.

4.88 and 33's myself.
3k at 70

 

Even wish I went with the next step lower

 

Will re-gearing change the speedometer or is it only read from the tires?

 

Depends if you have a 4 banger or 6 cyl.

 

4 banger

 

My speedo is off with gears and 33's

2009 4 banger

 

Now that I think about it, gearing should have nothing to do with it.
Has to come from the tires. Which is good because with 32 inch tires my speedo is dead nuts accurate according to my gps.

 

At 70 my speedo is off by 10-12 mph with 33" tires and 4.88 gears.

 

Speedo shows 70 but gps says 58-60 ish