Right now I'm riding on a set of 305/55R20 all terrains with the stock 3.73 ls running gears.

Im considering a gear swap to get some power back, I'm just stuck on getting 4.10's or 4.30's?

I don't plan on ever going to 35's so no 4.56's for me. I take a 3-4 hour drive out of town every month and my in town driving is more city than highway. Without trying the gears out I'm stumped! I don't want to do 4.10's and wish for more gear or vice versa with the 4.30's wanting less gear.

Now if the difference between the two is hardly noticeable I'm all over the 4.30's.
I'm hoping you people out there with a 4.30/33" , 4.10/33" tire combo here that could please chime in. If your running 4.10's do you wish you had a little more gear or is it just right?
My main concern is, I don't want to be screaming motor on the highway. But again if the difference between the two is hardly noticeable I probably will just go with a 4.30 running gear.

Does having a 20" wheel play into this question any?
I am thinking that maybe a 4.30 would help more?

 

My FX4 came with 275/55-20 rubber and 3.55 gearing.

Your truck has 305/55-20 rubber and 3.73 gearing.

My tires are about 31.9" tall new, yours are about 33.2" tall new.

My tires turn about 652 revs per mile. Yours about 626.5 revs per mile.

My driveshaft turns about 2314.6 revs per mile (or 2314.6 RPM at 60 Mph)
(652 X 3.55 = 2314.6 ... if TC locks in OD, that's about 1620.2 engine RPM @ 60).

Your driveshaft turns about 2336.8 revs per mile (or 2336.8 RPM at 60 Mph)
(626.5 X 3,73 = 2336.8 ... if TC locks in OD, that's about 1635.8 engine RPM @ 60).

Your truck's effective gearing with 3.73 and the slightly taller tires is still lower overall than mine with factory rubber.

The 4.10s will increase torque multiplication at some cost .... but then they'ld do the same for mine and I have no plans to change my 3.55s out.

http://www.1010tires.com/TireSizeCal...?action=submit

 

If your truck is a 4x4, then 4.30's are out of the question. They don't make 4.30's for the front. You need a reverse cut set for an 8.8. 4x4 trucks are limited to 4.10 or 4.56

 

With 373 gears I dont see the reason. I have 355 gears and 33 "tires and power is great , i think I would spend money somewhere else if I was not going over 33"tall

 

+1

I also dont think it would be worth it to switch out gears to 4.10's. it costs too much for such a little gain in performance.