Want to go bigger

OK so not having much luck, been under the jeep and the back diff has a tag but you can' read it or make it out at all as its rusted and there no tag at all on the front, I tryed the build sheet link again but it' only saying no information found...
Where can I go from here ?
Raise the tires off the ground. Make a mark with a sharpie on your driveshaft. Count the # of driveshaft revolutions while rotating one tire. The number of times the driveshaft rotates equals the gear ratio. If the driveshaft rotates about 3x, the gear ratio is 3.07. If it rotates 3 3/4 turns, the gear ratio is 3.73.
 
Ok I've just paid to open the Vin info on my jeep and it says my rear axel ratio 3.07, dosnt say anything about the front ?
 
Ok I've just paid to open the Vin info on my jeep and it says my rear axel ratio 3.07, dosnt say anything about the front ?
They’ll be the same. Front and rear are always the same unless a previous owner did something strange and ran different size tires front and rear. So, now you know where you are. That’s good!

Why did you have to pay to open the VIN info on your Jeep. Was it through teh link we provided? Or another site? Not sure why the Chrysler page didn’t work. You could have called them and asked what’s up with the site. They wil e-mail it to you for free.
 
When you give advice you need to qualify your response..... and we need to know what the OP wants to do. There is no wrong combination. There is only a wrong combination for you.... or me. Personally, after running 33s on my TJR for 9 years, I wish it had 3.73s instead of the Rubi 4.10s.
True, I do, depending on the time of day I sometimes get quite a bit shorter with my responses that is ideal. (as in I get lazy with the details, not short as in curt)
I've known people with the 5 speed for whom 3.73 and 33s was ideal, it greatly depends on where you live and how fast you like to go on the highway.

However running the jeep as a 4 speed with 3.07s isn't going to do you a lot of favors with the current price of gas. Being that under geared isn't going to help the clutch in 1st any ether. If it's a 42rle then things get even worse. I don't remember the best general rule for 31s on the 32rh trans but it'll be closer that's for sure. Now the number of miles you need to pay back the cost of that regear is high so, even if you half the clutch life it's still a long payback... Unless of course you enjoy the extra pep. I think it's more of a factor as you get into larger and larger tires (I'd kill for 5.38s instead of 5.13s) but that's not the topic of this thread ;)


I guess I will pile on...my previous X has 31x10.50/15 tires on stock steelies, no spacers, and no steering stop adjustments needed.

Don't know what to say, when my LJR was stock heigh on 3.75bs rims and 31x10.5/15 tires would grab the edge of the control arm and fender flair at full turn. Given I wheel with the sway bar off so I don't know it that made a difference. It did NOT grab on the street. I never did measure those rims but so the bs I was told could have been a lie. But they stuck out more that the moabs they replaced.


There must have been a time
when we could have said no.
 
Couldnt unlock the vin with links on here and just wanted to my ratio so paid an online site, cost a fiver so no biggy.
So from everything I've read I'm going to go for 31 1050 tyres, they look like they go slightly wider than stock arches which is what I want as I'm putting on 7" arches.
Ate you saying it will be a little slower off the line ? And will I have to slip the clutch a little for a smooth start ? And how will the be different at say 70 in 5 on the motorway ?
 
Last edited:
That was on a carbureted YJ, it got 25mpg in 4th at 70mph... My TJR gets 19mpg at 60mph. Go figure eh.
Lol that is down right incredible mileage.
Couldnt unlock the vin with links on here and just wanted to my ratio so paid an online site, cost a fiver so no biggy.
So from everything I've read I'm going to go for 31 1050 tyres, they look like they go slightly wider than stock arches which is what I want as I'm putting on 7" arches.
Ate you saying it will be a little slower off the line ? And will I have to slip the clutch a little for a smooth start ? And how will the be different at say 70 in 5 on the motorway ?
Yep more slipping of the clutch, and you may find that even the slightest head wind or up hill grade will have you going to 4th on the highway.

7" fender flares? That's like installing wings. Stock is 3" and Rubicons have 4" that'll be a different look for sure, who's flares are you looking at?


There must have been a time
when we could have said no.
 
That was on a carbureted YJ, it got 25mpg in 4th at 70mph... My TJR gets 19mpg at 60mph. Go figure eh.
I've wondered for awhile, what kind of roads do you have in your area? Is it relatively flat? Around her it's hill country. I'm going to try to drive with low rpms for a change and see what happens to my mpg.
 
Is it relatively flat?
no,

DSC_0058.jpg
 
Ate you saying it will be a little slower off the line ?
Yes, I ran 3.07s 33s for 8 years. I used 4LO all the time off road and starting was fine. I could run 60mph all day in 5th, 4LO. But starting around town did involve more clutch slippage altho in 8 years, 150K miles I never had clutch problems. 4LO resolves all the gearing problems of 3.07s unless you want to rock crawl.

On the highway.... or anytime in High... I never used 5th. But I did plenty of Interstate driving at 75, 80mph in 4th gear. Several trips from Yellowknife NT to Denver CO. No issues ever with 33s and 3.07s. Far from ideal but completely workable....