Best gear ratio for running 35” tires?

Reidminer

Reidminer

TJ Enthusiast
Joined
Jan 9, 2019
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Location
Syracuse NY
Hi everyone, so I recently bought a new tj(totaled my first one so I naturally had to get another). As it sits, it’s got stock axles running 35” tires on a 4” lift(all professionally installed). It’s the inline 6 5 speed manual, and currently, on the highway unless it’s a straight away 5th is a dog. In fourth, hills and anything are no problem doing 65-75mph @2200-2500rpms. So what would the best gears to do a swap? If any?

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Rob5589 said:
Based on hp/tq efficiency for the engine/trans/tire combo.
Click to expand...


So will running 5.13’s affect the lower gears at all? And what would optimal rpms be on the highway? I like having it around 2500 at most, is that the sweet spot, and would 5.13’s allow that in fifth?
 
Reidminer said:
Awesome, thanks!
Click to expand...
5.13 would be my recommendation as well, which the chart agrees with. I have 35s and will likely go with 4.88s, but the NSG370 doesn't have as tall of an overdrive ratio as the 5 speeds.
You'll probably be about 2800 RPM at 70 mph in 5th gear. For comparison, a bone stock TJ Rubicon with 6 speed does 2700 rpm in 6th gear at 70. So 5.13 is close to the deepest factory effective gearing offered, and will have significant torque at all speeds. You may end up starting from 2nd more, but the lower gears will all be very useable.



Check out this calculator: http://www.grimmjeeper.com/gears.html
 
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Steel City 06 said:
5.13 would be my recommendation as well, which the chart agrees with. I have 35s and will likely go with 4.88s, but the NSG370 doesn't have as tall of an overdrive ratio as the 5 speeds.
You'll probably be about 2800 RPM at 70 mph in 5th gear. For comparison, a bone stock TJ Rubicon with 6 speed does 2700 rpm in 6th gear at 70. So 5.13 is close to the deepest factory effective gearing offered, and will have significant torque at all speeds. You may end up starting from 2nd more, but the lower gears will all be very useable.



Check out this calculator: http://www.grimmjeeper.com/gears.html
Click to expand...
Great, thanks so much, that’s very helpful!!
 
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