Competition Gears vs. Tire Size pulling questions

[Got Smoke?]

I'm still green to all of the factors of setting up a truck for sled pulling. A friend of mine and I were discussing my trucks set up for pulling the other day.



He says that for 3. 55 gears that the 35" tires I'm currently running are better for sled pulling.



I figured that 33" tires would be better because it would be easier for me to turn them with hwy gears, than a set of 35" tires.



He says that 33" tires are better suited on trucks that run 4. 10 gears.



Could someone better explain this possibly?

 

[Cumminsman]

ok. i like the other responses better

 

[WadePatton]

What Nick is saying--is that dude is confused or trying to BS you. Lots and lots of people are just confused.



You should print out gear charts with your tire size, gear, and FD ratios plugged in. I think some of that stuff is at a 4wd site. You also have the high/low side of the xfer case. Gear chart will show you were high/low gears split.



What Nick said--you'll always get more engine revs per tire rev with a lower FD ratio (numerically higer). period. So then you need to figger out just what RPM's you want to turn at a given speed--or how fast you want your tires spinning at a given RPM.



Then operate your truck at the chosen RPM via gear/tire selection.



Math, the other white meat.

 

[Nate]

My question kind of ties into this.



Right now I'm running 315/75/16s with 3. 55s... . I find that the truck is fine with no load, but pulling ~7000lbs it slows it down quite a bit... I'm thinking of throwing some 4. 10s in..... are 4. 10s too low of a gear??



I'm running 4. 88s and 36s on my Jeep... though the motor has like 1/2 the power as my CTD :-laf

 

[Turbo Tim 1]

If you want to see what speed you are turning your tires look at the gear ratio calculator in my signature. In order to win you need to not break :-laf and you most likely need the most wheel speed if everything else is equal. If you line up with a guy that has 3. 55's and 35's and you have 4. 10's an 35's and your trucks are indentical he most likely will take you of course that's dependent on track condition weight class etc.



I ran a 10,000 lb class with all duallys this year and my 33's and 4. 10's did me good with a first, but at a different pull the guy with the 3. 55's 35's and 12 valver that turned a few extra rpm smoked me by 40 feet and I don't believe are hp were that much different. We both pulled in 3rd low. Does that mean the 3. 55's are a better gear? No, maybe the 4. 10's are stronger I don't know for sure, but I know any size tire will turn faster with 3. 55's.

 

[Sled Puller]

Mark, try a set of 31s, you might be surprised at the results.



For some reason Pullers think they need the biggest tire, the most weight, the highest hitch allowed. Those things are maximums, set your truck up for your HP and suspension range.

To answer your question you are right and hes wrong. Nice of you to post his name!!!

What number did you pull at Cynthiiana? I'll look at the game tape and decide what tire you need!!LOL :-laf

 

[WadePatton]

Nate- use the gear calculator to see what tire size you'd need to produce the same result as changing FD ratios. I'd rather change tires than gear sets anyday. Maybe someone has a spare set you can try. Much easier to change back.



4lo.com has some gear stuff.



I poked some numbers into it for some examples.

1800 RPM, . 73 (5th gear), 4. 10 gives 62. 6, 59. 1, 55. 5 MPH with 35,33,31 inch tires.

1800 RPM, . 73 (5th gear), 3. 55 gives 72. 4, 68. 2, 64. 1 MPH with 35,33,31 inch tires.



From that you can see that a 31 inch tire on 3. 55's comes out nearly the same as 35 inch tires on 4. 10's. And lots more.



Or you could figger all that for R's at a given speed etc. GO try it.

 

[Elite1]

Here is another good calculator:

http://www.rocky-road.com/calculator.html

 

[Got Smoke?]

What number did you pull at Cynthiiana? I'll look at the game tape and decide what tire you need!!LOL :-laf

Next to last. :{ But I beat Brad Racke! :-laf

Pulled 268. XXft. I'm running worn 35" tires right now. Got around 25-30% tread left.



Gonna try and borrow a set of 33" tread's for a pull this weekend.

 

[TurboTweaker]

my tire set up when i get time to pull. is a set of grooved baja claws aired down to 25 psi. bite hard on the soft tracks, and way to hard on the sticky tracks. but that just means i need more power to spin them huh sleddy?



The Fat Kid

Andy