Sooooo, everyone understands the weight of larger tires isn't the real issue right???

[Old-Raptor-guy]

Tire height is the real issue as it relates to power/loss of power. IF you don't know I will explain, but suffice it to say that the 37 package should come with 4.30 gears.

Could be I am wrong, so if some one has an argument based solely on tire/rim weight then go head please educate me.

 

[WTX]

Humor me with your explanation because I clicked this thread expecting much more.

 

[smurfslayer]

I clicked this thread expecting much more

So, the same as every other thread on the internet, is what I hear you saying... right

 

[heybear]

with all due respect, i would invite everyone who clicked here to check a gear chart.

and the see the actual rpm difference at various speeds with 4.10s and 4.30 (or whatever is available)

please draw your own conclusions.

 

[Yoshi]

According to tundra and chebbie owners, you only need 3.33 gears with a 10 speed tranny and any tire size.

 

[TurboM]

The diameter/circumference, gear ratios, weight, etc. of everything rotating between the engine and the tires has an impact on acceleration. Thought this was a given. Guess not...

 

[HighwaySentinel]

Tire height is the real issue as it relates to power/loss of power. IF you don't know I will explain, but suffice it to say that the 37 package should come with 4.30 gears.

Could be I am wrong, so if some one has an argument based solely on tire/rim weight then go head please educate me.

I don’t know. Please explain.

 

[Old-Raptor-guy]

A tire is a "reverse lever". A tire/wheel is driven from the center (at least in automobile applications). It is the exact opposite of getting a longer ratchet to get more leverage on a bolt. Imagine if the bolt was spinning the ratchet, the longer ratchet would have less torque at the end.

lets say we have an engine that makes 500 ftlbs of torque, with a transmission first gear ratio of 3:1 and a rear differential of 4:1

500 ftlbs into trans gets you 1500 out
1500 into the differential gets you 6000 ftlbs applied to the axle shaft.
now apply that to different tire/wheels
32" (has a 16" radius) would get that 6000 ftlbs down to the glorious number of 375 ftlbs applied to the ground
33 would be 363.6363
35 would be 342.857
37 would be 324.32

Now if we regear the differential to 4.2 we get 6300 ftlbs applied to the axle shaft.
which with 37's would give you 340.54 ftlbs to the ground. basically matching 35's

This is why people regear after getting bigger tires, they lost a bunch of torque and want it back. Think jeep going from 31's to 37's. it is also why you have to go to bigger axles if you make such a large change, factory jeep axles can't handle the amount of torque going from 3:73's to 5:30's

 

[Old-Raptor-guy]

The diameter/circumference, gear ratios, weight, etc. of everything rotating between the engine and the tires has an impact on acceleration. Thought this was a given. Guess not...

correct, but having seen a few threads where people were worried/comparing tire weights it seemed to me that many were not actually aware of the over all gear ratio change. That is why I didn't give an explanation in the original post, if I had a bunch of "yea I understand" responses then I was going to just let it die.

 

[CoronaRaptor]

Thanks for the explanation, while most of us are familiar with the concept, many many more are not, it's the same as some think they can offroad with 22" rims the same as somebody with 17" rims.