dont forget that even with 410s and 33 inch tires its still working harder, your 33s are not as light as the factory size tires...
rule of thumb is for every gear size you jump your rpms change by 300 so if your at 1800 rpms at speed x with 410 gears then youll be around 2100 at the same speed in the same gear with the same tires
I have the 5 speed and 33s and I went with 4.56 gears. I was shocked at first cause of how much higher my RPMs were, but after driving some more stick shift vehicles around and really paying attention to them, It's a lot closer to what most cars are geared like. The power accelerating is amazing with 4.56 gears and the Jeep seems much "happier" on hills on the highway. ALSO they leave the option of easily going up to 35s without another regear. and remember, you'll always wanna go bigger.
I have the 5 speed and 33s and I went with 4.56 gears. I was shocked at first cause of how much higher my RPMs were, but after driving some more stick shift vehicles around and really paying attention to them, It's a lot closer to what most cars are geared like. The power accelerating is amazing with 4.56 gears and the Jeep seems much "happier" on hills on the highway. ALSO they leave the option of easily going up to 35s without another regear. and remember, you'll always wanna go bigger.
My 5 speed xj goes down the highway at a lower RPM that my auto xj does. Both are stock, theres around 400 RPM difference at about 75mph
My 5 speed xj goes down the highway at a lower RPM that my auto xj does. Both are stock, theres around 400 RPM difference at about 75mph
The auto XJ has 3.55 gears usually and the late model 5 speeds have 3.07 always. That's where the difference comes from. The overdrive on them is only like .02 different.
Deeper gear will make the engine spin at higher rpms at all speeds thus burning more fuel
Totally depends on how "Efficient" the engine is that is powering your combination. Sometimes, an RPM increase of 300 to 500 RPM can make an engine more efficient, and produce better mileage, utilizing the power band sweet spot. Personally,,I dont get the "mileage" thing when dealing with an off road vehicle with big tires. Another overlooked issue is reciprocating mass increase with bigger,thus heavier tires, that has a huge effect on mileage and efficiency. There's a difference affecting vehicle performance between sprung vs UN-sprung weight. A lot of times, it just seems good sense to slow down a bit on the highway to get a little better mileage.. As an example,slow down from 70 to 60,,10 minute per hour cost in time,, and possibly 3 to 6 MPG increase in fuel efficiency. Jeep in not a "fuel mileage" vehicle,,"She ain't no Prius ya know"
I had no complaints whatsoever in an 96 AX15 4.0L with 4.56. Daily drove for years at highway speeds and rock crawled it in Eastern PA. I would happily do the same again. 4.10 might also be good, but 4.56 was pretty perfect in my mind.
I put 4:56 gears with Tru Tracs front and rear in my automatic XJ, hack and tap SYE, 4.5 IRO complete short arm kit, Bilstein 5100's, and new BFG 31 KM3's and I'm tickled with the complete upgrade. Even with the shorter tire, it works great, I wouldn't change a thing. 2250 RPM at 60, 2550 at 70. All kinds of power. Silver Lake Michigan
Just to add a little insight on the rpm vs mpg thing... with my 2018 Silverado 5.3 2wd, I drive 75 on the highway and get about 16mpg on 20x12s and big tires. That being said, when I tow my bass boat, I get 18.5mpg. Why, you ask? Because when I'm towing I'm doing 55-60mph, and the RPMs are around 1600. When I'm empty at 75mph I'm closer to 2000 RPMs. That 400 RPM difference is worth 2.5mph, even with an extra 2800lbs tied to the back of my truck. To summarize, RPM makes more of a difference than you think.
4.10:1 with an AX-15 and 33" tires will be closer to stock gearing than 4.56:1.
Check this tool out:http://www.grimmjeeper.com/gears.html Set up the stock vehicle on the left and try various combos on the right. Crawl speeds and highway RPM are displayed at the bottom
