Optimal tire size for 4.56s gears and 42RLE?
- Thread starter VAUGHN01TJ
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- 4.56 gearing gearing ratio tires
Well, I went from stock 31's to the 33's and didn't mind the loss of off the line performance. So from my perspective I'm going to ensure I have all the other $tuff I need and will do gears when I reach the confluence of need and available funds.
When my jeep is unhappy, it doesn't speak to me
In my search to determine what gear ratio is best for my usage, I've tried driving with and without the overdrive. On two lane roads, where speed limits are 45 to 55 MPH, I usually have the overdrive off. At 65 MPH and above, I use overdrive.
The PO of my Jeep installed a Banks cat back system. When I get around 3000 RPM, it gets loud, but this is probably near the peak torque.
2006TJ1
TJ Enthusiast
ErikOffroad
TJ Enthusiast
I’m just a little confused because
Stock was a 29 inch tire with 3.73 gears. If I switch to a 33 inch tire and install 4.56 gears I would still have deeper gears than stock. I thought that 4.88 or higher would possibly be excessive. I’m currently on 3.73 gears on 33 inch tires and yes I know it’s lacking power going up hills, but when I regear I thought the goal was to keep it close to stock parameters. ya I know I can probably benefit from deeper gears but I don’t want the engine screaming going down the highway.
Stock was a 29 inch tire with 3.73 gears. If I switch to a 33 inch tire and install 4.56 gears I would still have deeper gears than stock. I thought that 4.88 or higher would possibly be excessive. I’m currently on 3.73 gears on 33 inch tires and yes I know it’s lacking power going up hills, but when I regear I thought the goal was to keep it close to stock parameters. ya I know I can probably benefit from deeper gears but I don’t want the engine screaming going down the highway.
2006TJ1
TJ Enthusiast
Honest opinion from someone who didn't believe the regearing hype:
I thought my 3.73 gears were going to be fine with 33s (paired with the 42RLE) until I could get the funds to regear. I was estimating a year or two.
Long story short, I had the opportunity to work alongside a dragstrip mechanic to regear, all I had to do was provide parts. Ultimately, we decided that if I were to ever change tire sizes in the future, I'd be going down to a 32 to save some weight. After we got my Revolution 4.88 gears in, I thought it was a brand new Jeep. I could never go back to 3.73 and push off regearing for a year or two. It would be at the top of my list. City driving isn't that different, but it can pull hills and pass on two lane roads SO much better. Highway driving with 4.88 gears is a whole world apart from the 3.73s. If I'm not paying attention, I can easily get up to 75-80 on a highway with a speed limit of 65. With 3.73s, you know when you are accelerating because every single time you try to speed up, you can't until the trans downshifts.
Also, having chosen 4.88 gears rather than 5.13, I can confidently say that going to 4.56 gears would be a huge mistake. Every once in a while, trying to pull a hill on the highway for example, I could use a little more gearing. With 4.56 gears, it wouldn't be every now and then though, it would be all the time.
If you are going to run 33s with the 42RLE, at LEAST go 4.88. If you know you are never going to consider going down in tire size, then go with 5.13. You won't regret either one.
I thought my 3.73 gears were going to be fine with 33s (paired with the 42RLE) until I could get the funds to regear. I was estimating a year or two.
Long story short, I had the opportunity to work alongside a dragstrip mechanic to regear, all I had to do was provide parts. Ultimately, we decided that if I were to ever change tire sizes in the future, I'd be going down to a 32 to save some weight. After we got my Revolution 4.88 gears in, I thought it was a brand new Jeep. I could never go back to 3.73 and push off regearing for a year or two. It would be at the top of my list. City driving isn't that different, but it can pull hills and pass on two lane roads SO much better. Highway driving with 4.88 gears is a whole world apart from the 3.73s. If I'm not paying attention, I can easily get up to 75-80 on a highway with a speed limit of 65. With 3.73s, you know when you are accelerating because every single time you try to speed up, you can't until the trans downshifts.
Also, having chosen 4.88 gears rather than 5.13, I can confidently say that going to 4.56 gears would be a huge mistake. Every once in a while, trying to pull a hill on the highway for example, I could use a little more gearing. With 4.56 gears, it wouldn't be every now and then though, it would be all the time.
If you are going to run 33s with the 42RLE, at LEAST go 4.88. If you know you are never going to consider going down in tire size, then go with 5.13. You won't regret either one.
2006TJ1
TJ Enthusiast
It is common wisdom to go one gear step deeper when possible to improve slightly over stock parameters due to the added weight of the larger tires.
Which stock parameters should we go by if we are to follow them?
42rle / 29.5" /3.73 = 2052rpm @ 70mph
NV3550/29.5"/3.73 = 2320rpm @ 70mph (nearly 300rpm higher than the 42rle)
AX-15 / 29.5" /3.73 = 2349rpm @ 70mph (nearly 300rpm higher than the 42rle)
NSG370/29.5"/3.73 = 2498rpm @ 70mph (over 400rpm higher than the 42rle)
32rh / 29.5" / 3.73 = 2974rpm @ 70mph (nearly 900rpms higher than the 42rle)
Notice where Jeep put the early TJs with the autos. They were "screaming" right off the assembly line.
I have a 2004 TJ Unlimited with 205,000 miles on it. Every time I drive it I use moderately enthusiastic throttle input and it hits 4 grand in every gear up to OD. It just doesn't care.
And the early ones were "screaming" at those RPM ranges with the national speed limits not far removed from where they are now.
2006TJ1
TJ Enthusiast
Not screaming at all. Just zips right on up there seemingly without effort. I will say that I believe most TJ owners baby them under some misguided notion. No owner that I have even gone on a test drive with ever drives in an even semi spirited manner. That may not mean much until you know that number is over a hundred.
I once had a guy with a large JK Unlimited that he put a blower on show up complaining of lack of power. He drove it and babied the crap out of it lugging it. I swapped seats with him, wound it out to near redline in every gear and drifted the back end around corners with tires squealing at every opportunity. When we got back to the house, he admitted that his rig had plenty of power and I never heard another complaint about it again.
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Thank you for voicing your experience. When I was looking for a Jeep, I wanted the 4.0 engine. My mom had a '67 Grand Cherokee, and my son had '96 and '00 Grand Cherokees, all had the 4.0 engines. I thought they had plenty of "get up and go", but I have no idea what transmissions or gear ratios were installed.
My '05 with 4.0, 3.73, and 32" tires is a little disappointing in acceleration. I was convinced I wanted to go 4.88, but after reading about vibration issues at speed with deeper gears, I was re-thinking my choice. Now I plan to install the 4.88, and resolve any vibration issues that may arise.
This is how my son's '96 Cherokee ended its ownership (all occupants walked away uninjured)
2006TJ1
TJ Enthusiast
Glad to hear everyone made it out safely. That's a scary sight for sure & I bet that changed his outlook on driving (if it was your son driving).
I haven't experienced any vibrations since the regear, or at least I don't think I have. I have a weird, inconsistent whine coming from the front end only when I'm in first gear, but I'm fairly sure is the front DS u joints. Regearing can expose worn out u joints because the driveshaft is spinning so much faster than it was with a taller ratio.
2006TJ1
TJ Enthusiast
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?
Sorry if I get a little off topic, but yes, my son was driving. I get a call at work, "dad, I think I rolled my jeep". I frantically drive to the scene, and everybody is standing around, joking, making small talk. After I made sure everyone was OK, I asked my son " I think I rolled my jeep?". His reply was, "well it's only on the roof, and not a complete roll". Over a decade later, I can finally joke about the situation.