Power Wagon Registry

So a random thought popped in my head while stuck in traffic this evening, and I need some knowledge on my random thought. I know that with my 2012 if I go from stock to 35" tires the change in performance isn't noticeable. From what I've read 37" tires are noticeable, but not terrible. But what if a guy running the 5.7L Hemi and factory 4.56 gears did something crazy and went to 40" tires? I wonder what that would do to performance?

So those random thoughts lead to my question/thought. I know what 35's and 4.56 gears are like, but what would the gearing ratio be with 37" or 40" tires? I know that there's a spreadsheet calculator that I think Mogan put together before he bought his half ton Ram and disappeared, but I'm gear challenges so I thought I'd try to get everyone else's thoughts. Is 37" tires similar to 4.10's while 40's be similar to 3.73's?

While I don't have any tire change plans in the near future, my brain took me down this road today, and now I'm curious about what everyone else thinks?

4.56 gears
37 tires = 4.06 ratio
40 tires = 3.76 ratio

usmc369 wrote:4.56 gears
37 tires = 4.06 ratio
40 tires = 3.76 ratio

And just to add it in, the gear ratio/tire size graphs dont factor in the added rolling resistance of wider/heavier tires either.

Here is one I pulled off of google...

The way I look at it is:
Stock (non-PW Ram) on stock tires with 3.73 gears (a pretty common ratio) has about 30" tires vs Power Wagon on 37s with 4.56 gears:
(37/30)x3.73= approximately 4.6 so, 4.56 gears are a dang near perfect correction for going from stock base Ram tires to a 37" tire size.

By the same logic:
(40/30)x3.73= approximately 4.97 so, 4.88 or 5.13 gears would be more appropriate.

Conversely, to compare the performance to a non-Power Wagon:
(30/40)x4.56= 3.42 which is actually a very common stock gear ratio for 30" or so tired stock trucks. So, from a purely diameter vs gear ratio standpoint, 40s on a 2012 Power Wagon would be fine! But, the doesn't take into account tire and wheel mass, rolling resistance, air resistance at speed, etc. That being said, every time it's time to get tires, 40s are more and more tempting for me, LOL!

When looking at the above chart, don't forget that it assumes a 1:1 ratio in the trans so, your final drive ratio for highway cruising will differ dramatically due to the double overdrive of the six speed auto!

Thanks for playing along guys. Like I said, it was a random thought I had. The bummer with 2013 and older Power Wagons is I believe 4.56 is as low as we can gear our trucks. The 2015 up guys have more options. For some reason I like the idea of 37's and 4.88 gears, but that isn't an option for me.

04Ram2500Hemi wrote:Thanks for playing along guys. Like I said, it was a random thought I had. The bummer with 2013 and older Power Wagons is I believe 4.56 is as low as we can gear our trucks. The 2015 up guys have more options. For some reason I like the idea of 37's and 4.88 gears, but that isn't an option for me.

Yeah I think you guys can get 4.88's, no? I know the 5.13's are out for you, but I think 4.88's are an option.

04Ram2500Hemi wrote:Thanks for playing along guys. Like I said, it was a random thought I had. The bummer with 2013 and older Power Wagons is I believe 4.56 is as low as we can gear our trucks. The 2015 up guys have more options. For some reason I like the idea of 37's and 4.88 gears, but that isn't an option for me.

hehehe---that's the plan....4.88's Check, 37's Soon.

I don't see where going from 4:56 to 4:88 will justify the cost, need a bigger jump than that. I've test drove a couple of new regular 4wd 2500's lately, 6.4L and CTD, regular cab and crew. They were all turds compared to mine on 37's with 4:56 and a good tune; with them on bone stock tires. Transmissions probably play a roll in it as well but damn they felt weak.

THIS is one of the better calculators I've seen, gotta' enter your own numbers though.

With a quick calculation, 37's with 4:56 gears ~= 33's with 4.10 gears

2005-2013 Power Wagons have an AAM 10.5" rear axle, the tallest gear ratio currently available is 4.56:1. For some reason I remember a discussion over AAM releasing 4.88 or 5.13 gears, though I could be wrong.

2014-current Power Wagons have the larger AAM 11.5" rear axle, for which 4.88, 5.13 and 5.38 gears are available.

I looked into gears for a while and supposedly there is away to adapt 5.13s into a 10.5 but, I never could find concrete proof of it. Call it an unsubstantiated rumor I guess, LOL!

40" tires stock gears!


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NovA ProspekT wrote:THIS is one of the better calculators I've seen, gotta' enter your own numbers though.

I use that all the time. Just click on the drop down menus and pick a trans. You can also change the speeds and such on some of the charts to get different numbers for your own purposes.

People with the G-56, 6-speed manual trans, have less of an issue with tire size. 1st gear in the auto is 3.0:1. 1st gear in mine is 6.29:1. I actually bought/ordered the G-56 for that exact reason. If I ever put a lift & bigger tires, I have less of an issue with it.