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32" tires....What gear ratio?

V

ve6nn

NAXJA Forum User
Location
YUMA Az/Alberta Can.
Am going to install 32's under a RE 6130 lift. Have 96 XJ with 4.0 and Automatic tranny. 3.55 presently in it. Thinking of a 4.10/4.11 axle ratio.
The way I figure it I will be a little slower than present. Anyone know exactly what I will have with this ratio?
 
I have the RE 3.5 lift with 32". Didn't seem all that bad until I put the roof rack and tire up top. Now I can't get over 70mph with out it kicking out of overdrive!

With out the rack and tire, it did pretty good. I could tell it was working, but still getting about 15 MPG around town and back roads.

just my .02

I would like to swap, but $$

need more parts first..... rock sliders, skidz, etc, etc
 
Only want to run 32's.. this will be a daily driver and have to make a round trip from alberta canada to yuma arizona each year. also the wife has to be able to get in it. can't get too high a ratio or my gas mileage will go to hell. All I want is my present rpm at 70 mph with 225/15 tires when I get 32 inch tires on. I think ??? that 4.10 will give me that rpm. can anyone confirm or deny this?
 
I have the same RE lift and 32" tires on my xj. I regeared to 4.56s and haven't regretted it. If I stick to around 65 mph I get 18-19 mpg. That said, my fuel economy drops to about 16 mpg at 75. If you are SURE you're not getting larger tires in the future, and it's mostly for commuting I think the 4.10s are the right choice.
 
You're mistaken to equate RPMs with fuel mileage. Go with the 4.56s and you'll be a happy camper. Think about all the added weight your rig has and will continue to take on. The rotating mass of taller and heavier tires alone will drag down your motor more than you can imagine. Add in some decent bumpers and skids. Add in the additional wind resistance from having your rig that much higher into the wind and with that much more of the running gear exposed to the wind.
Just my humble opinion -
but my 33s and 4.88s combo is SCHWEET!
 
my vote (based on experience) is for 4.56 & 32s... as long as you don't want to drive over 80mph for extended periods of time, this ratio puts you right in the powerband.
 
Here is a few figures that I came up with for my XJ (97). The stock tires were 225/15 and at 60mph in 3rd gear (no overdrive) I had 2500rpm. I installed 4.56 gears and 31/10.50 tires which calculated out to 2965rpm which checked today 3000rpm at approx 60mph, so it seemed to work. I also had calculated 4.10 gears which should be 2660rpm for 31/10.50 tires and 2577rpm for 32/11.50 tires. This was all based on Goodyear ATS tire info from their Light Truck tire brochure. 4.10 gears should put you within 100rpm of your setup now if the 32/11.50 tires are actually 31.5 inches tall as Goodyears are. The figures above were calculated as percentages and are only ballpark accuracy but it did seem to work. Maybe someone else could give more accurate numbers but keep in mind that you will be pushing larger meats. The calc for 4.56 gearing with 32/11.50 was 2873rpm and 33/12.50 at 2786rpm, all 60mph 3rd gear rpm auto tranny. Hope this helps.
 
ve6nn: I just went from 4.10 to 4.56s and that was just for driving around town in phx so if that tells you anything...Also with 4.10 and hills your going to be downshifting alot especially if you try and maintain 65 and above(theres just too much drag from the heighth of the vehicle and weight)...At 70mph which is what I cruise at its like 2550 rpms and itll do that all day long plus I get like 250-260 to a tank... and you gotta love the passin power if you need it no downshifting just push the pedal and go :clap: ...Dont do the 4.10s you wont be happy trust me I said the same damn thing about a year ago yeah 4.10s and 32s itll be great what a load of crap that was :looser: ....
If your ever in phx Ill let ya take it for a test spin just to prove it...
themud
 
Do the math. Your XJ came with 27" tires. Divide 32(your new size tire) by 27 and get 1.185. Multiply 1.185 by 3.55(your stock gear ratio) and get 4.20. This is the ratio that would equate to the stock gear/tire combo.
4.56 would be slightly lower than stock. Go with this.
 
Thanks for all the advice. Have ordered 4.56 gears and have 32 inch tires ready to go on. All this happens the first week in November. Just to let everyone know that I do listen. Apprecitated all the different inputs.
 
Enjoy - glad to hear you aren't like some around these parts who hear 50 people telling them "this is the way it works" but strike out on their own and flub it up anyway...:D Refresh my memory; what lift are you putting on?
 
Yucca-man

RE 6130 4.5" lift
 
so with the same lift and 33's... would you suggest 4.88's?
 
If your rear axle will support that, sure. If you've got a C8.25" you're limited to 4.56 at the most.
 
well since the guy already had his question answered...i have a 5spd and 31s and i NEED to regear 3.07s suck especially with gas so high right now. I was thinking a ford 8.8 swap with 4.10 gears and then regearing the front to match. Will that setup work well or should i go lower since i have a manual trans??
 
you need not go as low since you have a stick
 
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