The 4.56 will rev higher rpms than the 4.10 at the same speed
The charts are the same…
Looks like Nitro makes a 4.30 ratio.
Those were discussed in one of the threads.
That is exactly the point. The chart is the same for any engine or transmission.
Yes, I have swapped Ring and Pinions on several trucks and Jeeps.
[/QUOTE]2022 JTRD
Stock Tire = 33
Stock Gear = 3.73
RPM on Chart = 2470
And
New Tire = 37
New Gear = 4.11 ( 4.10 )
RPM on Chart = 2427
Chart says your suggested 4.56 Ratio puts the RPMs at 2693.
4.10 with measured 37" tire drops 43 RPMs below oem spec.
4.56 with same tire increases RPMs by 266 at the same speed.
Running 43 RPMs below spec is not going to lug the engine and the actual tire size will shrink up to an inch with wear bringing the -43 rpms right back to baseline.
Increasing RPMs raises fuel consumption and wear on the engine in an apples to apples traveled distance.
Even someone "who fell out of a stupid tree"
can see which one ( 4.10 ) is closer to the oem spec.
Same results across multiple Tire/Gear Calculators confirm 4.10 is the closest to oem spec.
I have no doubts 4.10 is the best option.
40s on a 4.56 = 2491 RPMs only 21 over spec
I may not be a smart man, but gearing for a 40" when running a 37" wouldn't make me smarter...
Overland EcoDiesel comes with 255 = 32" tire and 3.73 gears
If you want to keep the same final drive ratio, tire change percentage = gear ratio change percentage.
My advice, don't do it. I have a JTR with 4:10's and 37's. I drove it for almost two years like that and learned to hate it. Just had a set of 5:13's installed and it restored my faith in the vehicle. I drive all over the country with it and with the large tires and 4:10's it was always in the wrong gear for the vehicles speed and RPM's at the time. It was okay around town but on highway and in mountains it sucked. The vehicle rarely saw eighth gear. I just finished a cross country drive with the new gears and it go as good or better mileage as before on highway and in all my side trips in mountains. The best part is the engine is not always looking for the right gear for speed and RPM's. It drives so much smoother without seeming to labor all the time. I was set on 4:88's because it would be back close to the 4:10's performance numbers when it came with 33's but my shop convinced me that the 5:13's were a better fix and they were dead right. I drove 70 mph typically coming back at 2250 RPMs and same mileage or better as before. At 75 it is at about 2500 RPM's on flat roads. You say you don't want to lose your top end but I would ask, how fast do you drive your rig? Just my opinion here but I would never go back to higher gears with 37's. Ever. Just a note here but this is the third set of gears Chassis Dynamics in Salem Oregon has done for me and their work is superb. Jim and Russ are rock crawlers and off-road specialists, and they know Jeeps. The cost was just under $3000 including a diff service to change gear oil after 1,000 miles. Good luck to you.
Don't care, he's making a second mistake. The first was buying a diesel.
