I preferred selectables for the same reason as anyone else. Better control over my rig in any condition and on any trail.

The ability to select which wheels get driven and which do not allowed me to chose the lines I wanted and to tackle them without more skinny peddle than was needed, and no broken parts.

YMMV

 

Thank you Frank, that is what I was looking for in an answer had not thought about it in that perspective, but that makes sense to me in that light.

 

I figured that part was sort of implied. But yeah, trail wise that's why they're nice.

 

TOTALLY this

 

FWIW, I got my gear sets from Frank at Serious, as well as the install kits. Couldn't be happier. Installed them myself, but word of warning, if you don't have the right tools and so on, take it to a shop. I actually had access to a lift and all the tools, as I was taking a college course at the time, and used it as a class project...

Also, if you're going to regear, do your lockers now. I left mine open due to budget constraints at the time, and I'm kicking myself every day since because of it.

 

Ok guys, I'm about tempted to sticky this because of frequent asking. I'm about to teach you the basic formula for Effective Gear Ratio. This is what your vehicle acts and feels like it has.
Now its OTD / NTD x CGR = EGR
OTD: Old Tire Diameter (stock size in inches)
NTD: New Tire Diameter (in inches)
CGR: Current Gear Ratio (what gears you have now)
EGR: Effective Gear Ratio (again, what your vehicle acts like it has)

Now, majority of our rigs came with roughly a 28" tire, this is the OTD.
A majority of Automatics have 3.55's for gears. This is our CGR.
Now let's say you want to add those 31" tires, this will be your NTD.

Now the fun part. 28 / 31 x 3.55 = 3.20:1
3.20:1 is what your vehicle acts like it has now that larger tires have been added.

"But what gears should I regear to?..."

Simple, start plugging in available gear ratios for your axle into the CGR slot until the EGR number comes as close to the stock ratio as possible. (3.55:1 for Automatic & 3.07:1 for Standard. Yes, the numbers won't be exact as stock but as close as possible)

By doing this, your vehicles powerband will be as close to factory as possible causing less strain on your engine and transmission. Basically, your vehicle will think and act like it still has stock tires even with the larger tires.

Any questions or trouble with the math, feel free to shoot me a PM with your Year, Engine, Transmission and tire size you wish to run (I have a conversion chart to work with metric sizes as well) and I will gladly run the math and give you your options.

Thanks for reading.

 

.

 

Awesome info! Thanks for adding that to the conversation!

Now just to muddy the water even more, is it worth running 4.56 over 4.88 with 35inch tires in order to preserve the R&P??? Are 4.56 gears/pinion substantially less prone to breakage than 4.88s?

 

No.
There are far too many "Friend of a Friend" stories about pinions exploding and killing dozens of Nuns & Orphans.

It really boils down to the driver, the line choose and the amount of skinny pedal applied.

 

There's an easier way to think of it.

Basic relationships are:

Y1/X1 = Y2/X2 or the inverse X1/Y1 = X2/Y2

Y = Gears
X = Tires

Y1/X1 (or inverse) = Current Setup (or known stock)
Y2/X2 (or inverse) = Equivalent new Setup (one unknown)

For relationship Y1/X1 = Y2/X2
If you want to know equivalent gearing to match stock (or what you have now) for new tire size:

Y1/X1 * X2 = Y2
Current Gear Ratio/Current Tire Size * New Tire Size = Equivalent Gear Ratio

Example w/ stock 3.55 gears and 28in tires, and you want to run 35s:
3.55/28 * 35 = 4.437

Thus, to maintain the same "feel" with 35in tires as the stock 3.55's with 28in tires, you'd need a 4.437 gear set. Larger tires are heavier, so even if you could get a 4.437 gear set, it would be prudent to go a bit "lower," i.e., rounding up to the next "lowest" which are 4.56's.

If you prefer a bit lower yet, you can check what the stock gear ratio would be to see if you'd be over gearing.

Example I have 35's (current tires), I am considering 4.88's (current gears), what would the equivalent be for a stock Jeep (i.e., would that be too much gear for the tires?)
4.88/35 * 28 = 3.90

A bit higher than 3.73's with the towing package, but you're turning a heavier tire, so good to go; however, if you were trying with 33's (32.5in actual):

4.88/32.5 *28 = 4.20, which could be considered too much gear and you may want to stick with 4.56's.

For inverse, X1/Y1 = X2/Y2
Similar can be done with the inverse to answer questions like: "I have X gears, what's the max tire size can I run?" For this, say you have 32.5's and 4.56's, and are considering moving up in tire size but don't know how far you can go without having to (read: probably want to) regear. Acceptable stock gear ratio w/28s was 3.55's, and you want to maintain at least that with larger tires.

28/3.55 * 4.56 = 36's. So, if you stay under a 36" tire, you'll maintain at least the same as 3.55's with 28's.

Prefer lower? Just use the 3.73 that came with the towing package.

28/3.73 * 4.56 = 34.2's.

Pretty easy.

 

Ok, that would work too. Not trying to degrade/belittle anyone here but I just gave the simplest formula available as not to challenge anyone's algebra skills. Lol

 

Haha yeah, I just like to arrange it so the result answers the question rather than doing trial and error, same thing though

 

Hum then why didn't you enlighten me sooner instead of waiting on Frank to do so

 

Because selectable implies that you use them when you want/need to? Like your front locker, I doubt you just run obstacles with it on all the time. Same applies to having the rear selectable.

 

Are you saying the 4.56 and the 4.88's are equal in strength for these applications?


I looked at both and it sure didn't look that way to me but its only an I6 for power and Tq I guess. I really have no issues with the 4.56 gears even after I picked up a set of trail tires and rims in 35" and beadlocks. They are off road only (used set of re-grooved Mudders) on the road I still run 33's.