Optimal tire size for 4.56s gears and 42RLE?

So if I did this right when using the gear calculator, it’s saying that with the 5.13 gears on 33 inch tires 3000 rpm equals 83mph. If that’s correct then I now see where you are coming from and ya 5.13 makes sense
 
ErikOffroad said:
So if I did this right when using the gear calculator, it’s saying that with the 5.13 gears on 33 inch tires 3000 rpm equals 83mph. If that’s correct then I now see where you are coming from and ya 5.13 makes sense
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Which transmission? Did you enter a 33" tire or the actual rolling diameter, which will be surprisingly less than we want to believe. My "33s" have a rolling diameter of 30". Ground to hub x2.
 
Thanks for the info jjvw. It looks like I need to get some 5.13 gears then. I know I’m going to have more questions about axle shafts and lockers but I will probably start a different thread for that later when I get close to purchasing parts
 
ErikOffroad said:
Thanks for the info jjvw. It looks like I need to get some 5.13 gears then. I know I’m going to have more questions about axle shafts and lockers but I will probably start a different thread for that later when I get close to purchasing parts
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Dana 30/35?
 
billiebob said:
BUT where will your RPM be in 3rd at 60mph? The 42RLE is all about compromize.
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42rle/30”/4.56=3064rpm@60mph/DD
42rle/30”/4.88=3279rpm@60mph/DD
42rle/30”/5.13=3447rpm@60mph/DD

42rle/30”/4.56=2643rpm@75mph
42rle/30”/4.88=2828rpm@75mph
42rle/30”/5.13=2973rpm@75mph
 
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So the question was optimal tire size for 4.56 ratios, where are we now? What is the question?

Not that I disagree jj, those rpms with 30s are pretty nice with a 0.69OD. Just wondering what the question is.
 
2006TJ1 said:
I don't know how accurate it is or not, but I think plenty of people are afraid of the effects of a heavy foot on gas mileage. I don't know why, considering it's bad enough when you baby the Jeep. Why not at least have fun with it?
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The problem with the whole gas mileage thing is you can baby the crap out of it until you get over 60 mph and then I don't care what you do, mileage is going in the crapper.

We had a friend that caravanned with us up to the Rubicon. About 10 of us in a line with a few towing with trailers. That put the speed limit at around 60 since towing speed is 55. At the first gas stop, he was baffled since he had swapped on 37's to try and lower engine RPM so he could drive faster and get better mileage (convoluted logic). He stated he should have needed fuel 75 miles ago according to what was normal and he still had a quarter of a tank. I explained that the lower speed does more for mileage than anything else that you can do practically.
 
mrblaine said:
The problem with the whole gas mileage thing is you can baby the crap out of it until you get over 60 mph and then I don't care what you do, mileage is going in the crapper.
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Exactly !!

I have done several 2K mile trips. Under 60mph, I can hit 20mpg..... almost. 75mph, I'm lucky to hit 15mpg. TJR with 33s.
 
billiebob said:
So the question was optimal tire size for 4.56 ratios, where are we now? What is the question?

Not that I disagree jj, those rpms with 30s are pretty nice with a 0.69OD. Just wondering what the question is.
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Those 30s are really ~33s. ;)
 
I gor ro say, Jeep did a great job delivering performance vs economy. Every change we do, heavier, bigger tires will kill gas mileage.

If you ever want to increase gas mileage, subscribe to a Jetta TDI Hyper Miler Forum. And start buying pizza cutters, lowering kits, and drive in bare feet.
 
2006TJ1 said:
So ultimately:
4.56- 31/32
4.88- 32/33
5.13- 33
5.38- 35

Essentially the information @Chris already posted in his regearing guide.
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Yep, that’s what I would recommend. Someone can say with 33s that 4.88 or 5.13 would work. In that case, it’s always better to go deeper with the gears in my opinion.

I don’t think you’ll ever hear someone regret having gone a little deeper as oppose to not deep enough.
 
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mrblaine said:
The problem with the whole gas mileage thing is you can baby the crap out of it until you get over 60 mph and then I don't care what you do, mileage is going in the crapper.

We had a friend that caravanned with us up to the Rubicon. About 10 of us in a line with a few towing with trailers. That put the speed limit at around 60 since towing speed is 55. At the first gas stop, he was baffled since he had swapped on 37's to try and lower engine RPM so he could drive faster and get better mileage (convoluted logic). He stated he should have needed fuel 75 miles ago according to what was normal and he still had a quarter of a tank. I explained that the lower speed does more for mileage than anything else that you can do practically.
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Makes sense. Calculating air resistance mathematically as a simple force at high speeds involves squaring the speed term, so any little change in speed has a much greater change in the force of air resistance.

That being said, sometimes you just have to run @ 75 mph and not worry about whether you're getting 20 mpg or 10.
 
mrblaine said:
What we need desperately is the .85 OD that the 6 speed has. That would set off a whole new set of gear discussions and we'd have to relearn everything all over again.
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I was talking to a friend that has a new Platinum F-150 with the Ford 10 speed trans, and that thing has 3 different OD gears. I think the 10 gear has a ratio of .64. Boy would that need some low gears.
 
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