I'm having my differential gone through next Friday and its an opportunity to pay a little bit more to swap out my 3.73 gear. I don't want to chance it with the Motive 4.30 as I hear too much about it being noisy. So I can go to either a 4.10 or 4.56. The 4.10 is about a 10% change, while the 4.56 is about a 22% change. My factory P275-55/20s measure about 31.5" and I don't have plans to really go bigger as this is a 2wd and just have a leveling kit. it pulls to 5,000rpms pretty good(custom MPT tune, efans, KN drop in, coated JBAs, Metallic 300cfm spun cats, factory 2013 OEM factory 3" exhaust. 1st gear tops a little over 40mph, 2nd gear changes out at 80mph(which seems very high).

Currently 75mph is 2,000 with 3.73.
With 4.10 it would be about 2,200.
With 4.56 it would be about 2,450.
I don't drive faster than posted hwy speed(i.e. - 65, 70, or 75mph).

However 90% of my driving is in town 40-60mph with RPMs between 1000-1600 most of the time.

4.10 or 4.56? Anyone running 4.56 with 31-32"tires have any likes/dislikes?

Thanks,
Rob

 

Rob, you've done a lot of research! Good on ya!

The only problem I see with going with the new gearing is that you'll be driving with more engine noise all the time and your fuel economy will be reduced. But, I can't say how much you'll lose in economy, because the engine won't be working as hard, even though it's running faster.

Honestly, unless you are planning to do some serious towing, I don't see why you'd want to go with the new gears. The 3.73:1 ratio was what my old 2005 KR had with a factory tow package. And, my stock tires were about the same diameter, actually just a bit larger.

Still, if you decide to change the gearing, I would not go above 4.10:1.

Anyway, that's my advice. Probably worth exactly what you are paying for it.

- Jack

 

Thanks Jack. I'm probably going to go with the 4.10. I like the 0-60 quick take offs and the 4.10 will get me a little more of that than my 3.73 but not be as drastic as the 4.56 on road trips. On a recent trip from Houston to the Texas hill country I calculated a 18.3mpg after topping the tank again. About 30 miles of that was locking out OD because of a scenic drive on a farm road that had some nice hills and speed ranged from 40-60mph.

 

Did you ever get gears ? I'm in the market for 4.10 or 4.56 looking to see what your mpg numbers are and rpms on the hiway. thanks

 

I did get the 4.10s and at 75mph i run abut 2,200 rpms. Milage did drop. At 75 i get about 17.5mpg on flat road. 95% of my driving is in the city so the quick take off from light is worth it. I think 4.56 would be too much unless you have a taller tire.