I don't think I've ever paid attention to mine but will check it tomorrow morning on the way to church.

 

okay thanks, i just think that 4:10's would change the rpms at higher speeds alot more than like 100rpm

 

Have a look. I still have the 3.92 in the truck from when it was new; it had 265/75r16 on it and it made for a good daily driver.

with 3.55
245/75R16 = 1757rpm @ 65mph
265/75R16 = 1691rpm @ 65mph
285/75R16 = 1630rpm @ 65mph
315/75R16 = 1574rpm @ 65mph


with 3.92
245/75R16 = 1940rpm @ 65mph
265/75R16 = 1867rpm @ 65mph
285/75R16 = 1800rpm @ 65mph
315/75R16 = 1708rpm @ 65mph


with 4.10
245/75R16 = 2029rpm @ 65mph
265/75R16 = 1953rpm @ 65mph
285/75R16 = 1883rpm @ 65mph
315/75R16 = 1786rpm @ 65mph

 

Tire size comes into play also, remember that. He may be runing a bigger tire or something.

 

When you are towing you will have the OD off. In 3rd gear (1:1) with the 3.55 gears in it now you will be at about 2300 @ 60 mph. With 4.10 gears you will be running about 2700 rpm @ 60 mph. The gears will definately help with acceleration but at highway speed towing you'll be running quite a bit more RPM's. For towing a few times a year I'd just stick with the 3.55's.

 

I had 4.10's and 275 tires. As a daily driver got 15 mpg, towing I got 8. Just giving real world results! I don't think 4.10's would be too low and when you do pull a trailer, you'll be glad for lower gears .

 

Huh, i thought it would change a bit more than that.

 

Nope thats it, it might not seam like much on paper but is does make a diff in the
practical world.

3.55 gears ......OD ...................In 3rd
245/75R16 = 1757rpm @65mph, 2546rpm
265/75R16 = 1691rpm @ 65mph, 2451rpm
285/75R16 = 1630rpm @ 65mph, 2363rpm
315/75R16 = 1574rpm @ 65mph, 2242rpm

with 3.92
245/75R16 = 1940rpm @ 65mph, 2811rpm
265/75R16 = 1867rpm @ 65mph, 2706rpm
285/75R16 = 1800rpm @ 65mph, 2609rpm
315/75R16 = 1708rpm @ 65mph, 2475rpm

with 4.10
245/75R16 = 2029rpm @ 65mph, 2940rpm
265/75R16 = 1953rpm @ 65mph, 2830rpm
285/75R16 = 1883rpm @ 65mph, 2729rpm
315/75R16 = 1786rpm @ 65mph, 2589rpm

with 4.56
245/75R16 = 2256rpm @ 65mph, 3270rpm
265/75R16 = 2172rpm @ 65mph, 3148rpm
285/75R16 = 2094rpm @ 65mph, 3021rpm
315/75R16 = 1987rpm @ 65mph, 2879rpm

with 4.88
245/75R16 = 2415rpm @ 65mph, 3499rpm
265/75R16 = 2324rpm @ 65mph, 3369rpm
285/75R16 = 2241rpm @ 65mph, 3248rpm
315/75R16 = 2126rpm @ 65mph, 3081rpm

 

Your numbers are close, and I agree with you leave it as is.

 

I'm turning about 2500 rpm at 65 mph in 3rd gear but I think my speedo is off a little, I believe I was doing around 70 mph. I'm going to check it wth my GPS when I get it back from my GF. For whatever reason I didn't think about pulling it in 3rd gear.

I believe I will pull the trailer and see what the truck does, I'm also ordering a SCT from Hemifever today and see if it makes a difference as well.