looking for some advise

punkrockford · Oct 1, 2013

Just drove the truck from phoenix to Prescott valley. stock tune minus the dpf. truck would go up to 35-40psi of boost when going up hills and would stay at around 20-25psi when maintaining 75 up the hills. coming back down is would hold at 5 to 10. I don't remember ever seeing my boost gauge that high before. I am assuming its because the truck has to work harder to keep the speed up when turning 37" tires. Since i am without head studs I am worried about the boost being that high. it never really hit 40 but it was close. Not to mention i was getting about 9mpg. so I am thinking 4.10's or should I go to 4.56 i was keeping my rpm at around 2000-2500. based on this what do you guys think. I only want to put gears in it once. lol

P.S. i still am running the stock air cleaner assy.

RedRice589 · Oct 1, 2013

I would think 4.10's would be fine but that's just me.

01PSD · Oct 1, 2013

Pretty sure you're not supposed to run a stock tune without the DPF in place.. :shrug:

RedRice589 · Oct 1, 2013

Lol I think he means stock power level Dpf removed

punkrockford · Oct 1, 2013

01PSD said:
Pretty sure you're not supposed to run a stock tune without the DPF in place.. :shrug:

Its a spartan tune that is stock but removes the dpf.

01PSD · Oct 1, 2013

Ohhh I gotcha.

sctreeguy · Oct 2, 2013

Where are you located? I have 4:10s been thinking about trading for 3:73

punkrockford · Oct 3, 2013

im in phoenix, i dont have 3.73"s i have 3.55's

RedRice589 · Oct 3, 2013

Well there's your problem!!, 3.73's would help but I would go for a 4.10 personally truck will have balls then buddy no lugging prolly gt 12-14 mpg after that. Just what I think though

punkrockford · Oct 4, 2013

I guess i am wondering if i should go with 4.10"s or jump all the way to 4.56" or is there a choice in between?

punkrockford · Oct 4, 2013

So knowing that math is the key to everything we do I figured I would take the mathematical approach. What do you guys think? So the stock tires 275 65 r20 = 34.1 inches. I have increased tire size to 37" so 34"/100% =37"/X% so I have to solve for X. If I multiply 100 by 37 then divide by the original tire size of 34 I get 109 (rounded up from 108.8). Then if I multiply 3.55 (original gear size) by 109 I get 3.86. seeing how that gear ratio is not available I go up to the next size which would be 4.10. Does this make sense or am I crazy? I am not sure but I think i just found a use for all that algebra I took in high school....lol

RedRice589 · Oct 4, 2013

Uhhh headache! Well there's guys that say 3.73 work great and guys that regear heavily up to 4.56 there are 4.10, 4.30, 4.56, and 4.88, if you go to a gear shop there may be more idk about your math I just liked the power I had with 4.10's and 35's my 3.55's on stock tires lugged and I hated it even running empty. I had my 16k 5th wheel behind me and left my rise on all the way to the mountains of Virginia. Just me buddy I'm not a math wiz.

punkrockford · Oct 8, 2013

I think i am going to go with 4.10's with my 37"s after i realized they are only 3" taller then the stock 20's what size tires were stock on your truck that you put 35's on?