Gear ratio poll for 37” tires on 17” wheels 3.6 gasser

[Badweather]

Looking for consensus on ideal gear ratio for 37” tires. I just installed Mickey Thompson Baja Boss AT with my stock Mojave 4.1 gears. So far seems fine but curious what others have done. My Jeep is a daily driver and off road is fire roads or sand dunes no heavy rock climbing. I’m in Wisconsin so elevation is 700 and not a lot of hills.

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[PuddleJumper]

5.13 is a bit crazy to me, especially with a 8 speed. If we were all still stuck with 4,5, and 6 speed autos or manual it would make more sense to me. I'd say as long as you fall in a colored square, mechanically your fine. Its just to personally preference as to what's your taste.

Generic list - 65mph at 1:1 trans gear.

 

[Badweather]

Thanks PuddleJumper the color coding really makes it clear

 

[JT1]

5.13 is a bit crazy to me, especially with a 8 speed. If we were all still stuck with 4,5, and 6 speed autos or manual it would make more sense to me. I'd say as long as you fall in a colored square, mechanically your fine. Its just to personally preference as to what's your taste.

I don't think that's the correct chart unless we are looking at 85mph. Even my 6speed on 37s with 5.13s isn't turning RPM like that.

EDIT* This above chart is for a 1:1 gear ratio, so 6th gear in an auto.. useless for determing highway RPMs at a given speed..

this is the chart for 8th gear.

 

[Wheelin98TJ]

5.13 is a bit crazy to me, especially with a 8 speed. If we were all still stuck with 4,5, and 6 speed autos or manual it would make more sense to me. I'd say as long as you fall in a colored square, mechanically your fine. Its just to personally preference as to what's your taste.

That chart is either for 97 MPH in 8th gear () or it's for 65 MPH with no overdrive.

 

[Paulyester]

I'm about 2100 RPM at 70mph with 4.88 and 37's

 

[PuddleJumper]

That chart is either for 97 MPH in 8th gear () or it's for 65 MPH with no overdrive.

i ignore the rpm range on that sheet cus its not transmission specific. its set at like 100 or 95 mph

edit: 65 mph with 1:1 gear

 

[PuddleJumper]

I don't think that's the correct chart unless we are looking at 85mph. Even my 6speed on 37s with 5.13s isn't turning RPM like that.

EDIT* This above chart is for a 1:1 gear ratio, so 6th gear in an auto.. useless for determing highway RPMs at a given speed..

this is the chart for 8th gear.

its a generic range for 100 or 95 mph i believe

65mph at 1:1. Its set that way to take transmission variety out of the equation because all road trucks should have a 1:1 gear and a 65mph capacity. so for you this would be your rpm in 6th gear paired to your respective tires and gearing. Its accurate for my stock mojave

 

[Wheelin98TJ]

its a generic range for 100 or 95 mph i believe

It's what I said previously.

1:1 at 65 MPH.

Or I suppose it could be 0.67:1 at 97 MPH, but 1:1 at 65 seems more likely.

 

[PuddleJumper]

I'm about 2100 RPM at 70mph with 4.88 and 37's

what gear? thats important

 

[PuddleJumper]

It's what I said previously.

1:1 at 65 MPH.

Or I suppose it could be 0.67:1 at 97 MPH, but 1:1 at 65 seems more likely.

so for us it your rpm range in 6th gear at 65. which seems close enough to me.

 

[MPMB]

4.10s with 37-class tires. MPGs definitely took a hit.

It's not super annoying yet, although there seems to be more RPM hang around 4th-5th gear when accelerating.

Some day I'll regear, probably 5.13s.

 

[JT1]

so for us it your rpm range in 6th gear at 65. which seems close enough to me.

But when geared correctly it won't be in 6th gear at 65 unless your are climbing a huge grade or accelerating faster, so the number doesn't help anyone figure out anything.

Top gear is what almost everyone references in threads like this.

With the auto, 4.88 or 5.13s for 37s, unless there is a use case that pushes you out of those choices.

 

[Zachanadandy]

I voted 4.56 as it would be ideal for me (I do tend to set the cruise control at 85mph on roadtrips) but figured I'd also post as I absolutely will not be regearing the mojave on 37s. The gain going to 4.56s from 4.10s is negligible in my experience and at a cost of $2500+ locally for a regear it just isn't worth it. The thing still sees 8th regularly, has no problem climbing grades at 80+mph, and will still hit 100mph even in the dirt with ease. It's not the rock crawling rig as the JLUR on 39s is way better there, but even on rock trails it isn't hurting for more gearing. Our 1st gear is so low with the 8 speed we can easily run gears on the much take side than you could ever dream of in a TJ, YJ, JK, etc.

 

[JT1]

I voted 4.56 as it would be ideal for me (I do tend to set the cruise control at 85mph on roadtrips) but figured I'd also post as I absolutely will not be regearing the mojave on 37s. The gain going to 4.56s from 4.10s is negligible in my experience and at a cost of $2500+ locally for a regear it just isn't worth it. The thing still sees 8th regularly, has no problem climbing grades at 80+mph, and will still hit 100mph even in the dirt with ease. It's not the rock crawling rig as the JLUR on 39s is way better there, but even on rock trails it isn't hurting for more gearing. Our 1st gear is so low with the 8 speed we can easily run gears on the much take side than you could ever dream of in a TJ, YJ, JK, etc.

The difference between 4.88 and 4.56 in top gear at 85 is about 150rpm. And 4.88s in 8th are not much different than your 4.10s at 85 in 7th.

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