3.73 gear ratio based on what tire?

[RHINO79]

So which gladiator factory size tire actually has the 3.73 gear ratio, the 245/75/17 the 255/75/17 or the 285/70/17 being they offer 3 different size tires I'm guessing the 3.73 is based of the smaller diameter tire, the 245/75/17

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[PuddleJumper]

Not necessarily. The willys can come with 3.73 but still standard with 285/75in mud tires. the tow max i believe comes with 4.10s and wide axle but still 245/75. so there isn't a dedicated tire size to the 3.73 that I'm aware off. Anywhere from 245/75 to 285/75 is acceptable. In fact some 35s if on the lighter C load range wise pair just fine as well.

 

[Wheelin98TJ]

They all have 3.73 except:

Rubi gas
Mojave
Max Tow

 

[Labswine]

My Overland has the 255/70R18 with the 3.73 gearing. It's what the factory gave me.

 

[MPMB]

Gear ratios are calculated based on engine/transmission/rear end gears, and has nothing to do with tire size.

 

[ZeeJay]

3.73 represents final drive @ differential i.e. how fast axle shaft will make revolutions. Any tire size can be mounted. Tire size however will determine final drive to ground.

 

[Stan H]

So which gladiator factory size tire actually has the 3.73 gear ratio, the 245/75/17 the 255/75/17 or the 285/70/17 being they offer 3 different size tires I'm guessing the 3.73 is based of the smaller diameter tire, the 245/75/17

Rubicon Gas comes standard with 285x70Rx17C 's when it comes to the models with the 3.73 gearing . I think tire size changes depending on what model you buy. As stated Rubi ,Mojave,Maxtow have 4.10 gears. As standard option.
I am not familiar with what is in the diesels as to axle ratios or tire sizes.

 

[MPMB]

3.73 represents final drive @ differential i.e. how fast axle shaft will make revolutions. Any tire size can be mounted. Tire size however will determine final drive to ground.

The first half is correct. Tire size is completely irrelevant to gear ratios.

A 4.10 ratio is for every 1 rotation of the axle, the engine spins 4.1 times. It doesn't matter if there's a 31" or a 40" tire on that rear end, those relationships will not change. The difference will be how many times a 31" tire will revolve over the same distance versus a 40" tire. And that will affect the RPM/Speed ratios.

 

[Wheelin98TJ]

The first half is correct. Tire size is completely irrelevant to gear ratios.

A 4.10 ratio is for every 1 rotation of the axle, the engine spins 4.1 times. It doesn't matter if there's a 31" or a 40" tire on that rear end, those relationships will not change. The difference will be how many times a 31" tire will revolve over the same distance versus a 40" tire. And that will affect the RPM/Speed ratios.

Tire size impacts final drive ratio is what ZeeJay said.

3.73 represents final drive @ differential i.e. how fast axle shaft will make revolutions. Any tire size can be mounted. Tire size however will determine final drive to ground.

 

[CrazyCooter]

You are all wrong in one way or another........

The differential gear ratio determines how many "driveline revolutions" to a single revolution of the axle shaft/tire.....I should elaborate for CYA that this isn't accurate in the case of a portal axle where there is usually further reduction in the portal hub.

The tire diameter affects the number of axle/tire revolutions per mile. Except for portal where this number is also a factor of the reduction in the hub.

Differential gear ratio, trans gear ratio, portal ratio, and tire diameter ALL determine how many revs the engine turns per mile or at a given road speed.

 

[ZeeJay]

The first half is correct. Tire size is completely irrelevant to gear ratios.

A 4.10 ratio is for every 1 rotation of the axle, the engine spins 4.1 times. It doesn't matter if there's a 31" or a 40" tire on that rear end, those relationships will not change. The difference will be how many times a 31" tire will revolve over the same distance versus a 40" tire. And that will affect the RPM/Speed ratios.

All of what I said correct and it’s not engine rotation it is pinion rotation. 3.73 represents 3.73 revolutions of pinion to 1 revolutions of ring gear. How does engine crank revolution relate to final drive when there 8 speeds between the two. How is your explanation any different than mine. I said tires will alter final drive to ground, that is whole other subject.

 

[MPMB]

Tire size impacts final drive ratio is what ZeeJay said.

Which has nothing to do with the OPs question.

 

[MPMB]

All of what I said correct and it’s not engine rotation it is pinion rotation. 3.73 represents 3.73 revolutions of pinion to 1 revolutions of ring gear. How does engine crank revolution relate to final drive when there 8 speeds between the two. How is your explanation any different than mine. I said tires will alter final drive to ground, that is whole other subject.

Right, the pinion rotation; I was working on the assumption of a 1:1 ratio coming out of the transmission. My default is thinking of a 4-speed manual. JT has a final drive out of the transmission of .8 or .6 something, I don't remember.

Talking about final drive ratio is not addressing the OPs question and also adds confusion when you're not clear because final drive ratio is usually referring to the transmission final gear or the ring & pinion.

Tires can manipulate ratios, experienced by the impacts of RPMs/MPHs (fuel usage is ignored), not the actual mechanical ratios. Because tires can be swapped out easily, and also inconsistencies between mfgs in sizes, tires are a poor baseline to use in gear ratio discussions.

So when the OP asks if a tire size is how you determine what the gear ratio of a JT is, the correct answer is: tire size doesn't matter. It's mechanical pieces from the factory, unless aftermarket parts were put in, in the determination of gear ratios.

 

[Zachanadandy]

Which has nothing to do with the OPs question.

It has everything to do with the OPs question, the OP is looking for the perfect factory ratio of tire size to gear ratio by the wording of the question, which is affected directly by tire size. The problem there is the factory doesn't have an exact formula. As mentioned you can get 285/70/17s or 245/75/17s with the 3.73 ratio. If you bring the JL factory options in to the conversation you can get 3.45s paired with 285/70r17s or 4.88s paired with the same. There is no 1 size fits all. With the 8 speed you can get away with a much wider range of dif ratios vs tire size than you ever could in a JK. This question just sounds like another way of asking which size matches with which gears to "drive like stock". Again that math is all over the place. 3.73s with 32s is geared almost identically with 4.10s and 35s. 3.45s and 32s is like running 38s and 4.10s. 4.88s and 33s is like running 5.13s and 35s. Geared "like stock" is as wide a range as the suggestions you'll get when you ask which gears you should run with 37s. Anywhere from 4.10s to 5.38s paired with 37s is geared "like stock" depending on the model and options chosen.

 

[Badunit]

Was the end goal of the original question simply to know which trims have 3.73 (which was answered in the middle of all those posts) or was it a question of optimum differential ratio for a given tire diameter (which is a loaded question that cannot be answered except as personal opinion)?

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