6 speed/Cummins/315, which rear end ratio?

[canonfan]

I'm going to purchase an 04 or 05 QC SB 4x4 with the six speed and plan on putting 315 BFG's on it first thing. Should I go with the 4. 10 or would the 3. 73 be fine?



I've been told that with the Cummins I won't notice any power diference like I have on other trucks when going up a few tire sizes. But, I want to have it matched so that everything lasts and performs like it should i. e. rpm range and what not.



Thanks!

 

[Spooled-up]

I personally would go with the 4:10's if you're going to run the 315's. The way I understand it, you'll end up with approximately a 3:73 final ratio if you run this combination. There is a calculator out there that I've never been able to get to work on my computer that someone will surely post. I've got the 4:10's on my truck with the stock tires and it's geared way too low for me. I don't tow with my truck yet, but I will someday and I'll easily be able to tow with the 35" tires I plan to put on.

 

[abdiver]

But, I want to have it matched so that everything lasts and performs like it should i. e. rpm range and what not.



Thanks!

Then wouldn't you be better off leaving is stock. The auto manufactures spend lots of money designing their vehicles to perform and last. Sure sometimes especially with new designs their are bugs to work out.



Luck in whatever you decide.

 

[wyosteve]

fwiw, I run 315's w/ 3. 73 as you can see from my sig. I pull some kind of trailer several times a month. This past Sat. I hauled 5 ton of hay plus trailer weight gave me about 14k total. Have no trouble running 70 or better here in relatively high altitude. 70 puts the tach about 1900. I think you'll be fine with 3. 73's esp. w/ the 6 spd.

 

[CTA]

I'm going to purchase an 04 or 05 QC SB 4x4 with the six speed and plan on putting 315 BFG's on it first thing. Should I go with the 4. 10 or would the 3. 73 be fine?



I've been told that with the Cummins I won't notice any power diference like I have on other trucks when going up a few tire sizes. But, I want to have it matched so that everything lasts and performs like it should i. e. rpm range and what not.



Thanks!

Canonfan ... I have an '03 3500 QC SB, SRW w/the 6-speed and 3. 73 LSD axles. I just went from the stock 265 to the 285 and using the calculator found at BF Goodrich home page I am now effectively running around 3. 61. If you are going up to the 315, I would agree with Spooled-up and opt for the 4. 10. If you want to see what your effective ratio will be, check out the calc at BFG.

I ordered my truck w/the 3. 73 gears and although I am extremely satisfied with the truck, if I had it to do over again, I would order the 4. 10 axle the next time around! I think I noted something like 150+ rpm difference between the 3. 73 and the 4. 10 trucks with the 6-speed when test driving them.

I tow a fair amount myself but just put the tires on a few weeks ago and then left home (without my truck) so I have not really had a chance to see how much difference it will make. I suspect that what I may have lost in my advantage in gearing will soon be overcome by the Six-Gun Bundle I am about to install. I will be hauling a 3 ton camper from VT - MD and back at the end of the month, I'll know how much difference my change will have made then.

I have no desire to "lift" my truck or "cut" out fender wheels so I can run larger tires, I use it to tow too often and for practicality reasons, the 285s are more the sufficient for my use. I just wanted to "fill" the wheel wells a little more, that's all.

 

[Motofreak]

Have the 315`s with 6sp and 3. 73's. It`s fine. I pull 10k a couple times a month. No problems at all. Think fuel mileage.