Tazer JL - more than just a tire size programmer!

CarbonSteel

Well-Known Member
Joined
Jul 21, 2019
Messages
1,855
Reaction score
2,088
Location
Colorado
Vehicle(s)
2019 Jeep Rubicon Unlimited
Vehicle Showcase
1
I have 4.88 in my JLUR on STT Maxx 37's and 2100 rpm running 70 in 8Th sounds about right. speed limit around here on the interstate is 75 and I normally run about 2100-2300 RPM. in 8th. With the stock 4.10's I would sit in 6th and I would have to manually shift it into 7th and depending on the wind it would be happy there. If I manually forced it into 8th it would kick it back down to 6th.
It is about the same for mine, just slightly higher RPMs (maybe 2300-2400) at 75MPH, but that is likely due to the BFG K02'S being a short 37.
 

Zandcwhite

Well-Known Member
First Name
Zach
Joined
Sep 4, 2019
Messages
1,281
Reaction score
1,870
Location
Patterson, ca
Vehicle(s)
2019 jlur
It is about the same for mine, just slightly higher RPMs (maybe 2300-2400) at 75MPH, but that is likely due to the BFG K02'S being a short 37.
It all comes down to use. We do a lot of road trips through states that have speed limits of 75-80mph. Most times the cruise is set at 85mph+. With our 37’s and 4.10’s it holds 8th at those speeds no problem as we are in the 2100-2300 range. On 4.88’s we’d be pushing 2500-2800 rpms. At the speeds we drive regularly, we would lose fuel economy (or be forced to slow down). The 4.7-1 1st gear and 4-1 transfer case mean plenty of gear reduction off road. I could see 4.56 as a happy balance on 37’s for speed and a little more 8th gear at lower speeds, but the benefit of 1 gear ratio isn’t worth the expense in my opinion. Some guys swear you need 5.13’s with 37’s, but 2400rpms at 75 just doesn’t sound efficient to me.
 

CarbonSteel

Well-Known Member
Joined
Jul 21, 2019
Messages
1,855
Reaction score
2,088
Location
Colorado
Vehicle(s)
2019 Jeep Rubicon Unlimited
Vehicle Showcase
1
It all comes down to use. We do a lot of road trips through states that have speed limits of 75-80mph. Most times the cruise is set at 85mph+. With our 37’s and 4.10’s it holds 8th at those speeds no problem as we are in the 2100-2300 range. On 4.88’s we’d be pushing 2500-2800 rpms. At the speeds we drive regularly, we would lose fuel economy (or be forced to slow down). The 4.7-1 1st gear and 4-1 transfer case mean plenty of gear reduction off road. I could see 4.56 as a happy balance on 37’s for speed and a little more 8th gear at lower speeds, but the benefit of 1 gear ratio isn’t worth the expense in my opinion. Some guys swear you need 5.13’s with 37’s, but 2400rpms at 75 just doesn’t sound efficient to me.
LOL - no way I would see 8th gear (not even 7th) or 2100-2300RPMs with 37's and 4.10 gears. I didn't see that with 35's.

With a 3.6L and 37's, 4.88 is the sweet spot for me. Your mileage may vary.
 
Advertisement

Hothead Headliners
 
Advertisement
Top