jsmith823

Hey everybody, I have a few quick questions. First, I am planning on purchasing another XJ as my personal vehicle and want to do some mods to it. I am planning on buying the older model (84-96) 4x4. What I want to know is if I were to put a 4.5" suspension lift on said jeep would I be required to change any gearing? I have heard that any lifts 4.5< have to be re geared. Also, I am planning on buying at's to put on the factory rims, would I be able to fit any size tires (31"-33") on the factory rims as long as it were made for a 15" rim? Plus, how much MPG would I loose by doing these two mods? I'm not talking about like BFG mt, but the BFG a/t ko.

90xjcjf

I have a 1990 xj w a 4.5 and it is stock gears in both diffs. Drive shafts r stock to. I'm running 32x11.50's did have them on the stock laredo style rims but the offset made them rub when I turned and the rear rubbed when I flexed it out. But I got the new rims, black rock style steel, and the rear rubbed on the body so I just did some cutting w the saws all! Mine is a daily driver to. 31x10.50's would be perfect for just mild muddy trails.

90xjcjf

And I had the same tires u want on mine. I did go to a more aggressive thread

jsmith823

I know this is a bad question considering what I want to do with it, but what kind of MPGS were you getting?

90xjcjf

Not much worse than stock. I got a 4.0 so it's a gas hog n e way. I haven't really tested my mpgs for sure because I go on trails to much to get a good idea. Sry I'm not much help on that. But it sure is fun w the lift and tires. But I would eventually get aftermarket rims.

Metmknice

With 31's your MPG gain would be minimal with stock gears, but will be affected. I definitely recommend a better AT tire. Such as Bridgestone Dueler A/T (REVO/REVO2 are my #1 pick of AT tires), Yoko Geolander AT-s, or even the GY MT/r kevlar.

xjguy71

I have an 88 xj. Rough country 4.5" lift. Im running 31/10.50/15. Havnt noticed any signifigant mpg loss. Little to no power loss with 31's. You'll only need to get a gear job if your gonna run 33 or bigger. You'll hate the power loss with stock gears if u run 33s

Nperryman

Not to hijack your thread but would that be the same thing with a 98 cherokee, the barely noticeable mpg change?

xjguy71

If you keep your tire size to a 31" your stock gears should be good on a 98 also. Mpg will be about same. Maybe a little loss. Not much though.

xjguy71

I get about 19-21mpg wth 31" tires on my 88. I still have stock gears.

jsmith823

What about if I were to get mud terrains? How bad are they on gas?

98Plum Crazy

I have a 98 with now about a 6.5 lift and 33*12.50 on stock rims, just need rc spacers and prolly wanna plan on sye or hackntap like i did, still have stock gears and dont see much worse mpg on bfg km2's.

SKidder

96 4.0ho automatic with 4.5inch lift and 33 inch duratracs and stock gearing, I got 14.7 (highway) on my last road trip. I hate the power loss but since this isn't my DD I don't really need to regear. Downside is I barely have enough power to spin the tires, I just put it in low range when I get off pavement.

00-buck

I ran 4.5" lift with 33's for a while on a stock geared 88 in town red lights everywhere averaged 13-14 mpg had to keep in drive od sucked ... ran 31's also same lift same milage just more pep ran both tires on 15x8 rims

smokerkenny

i've also got an 88 w/ a set of worn-down 31x10.50x15 bfg ko's on tj canyon wheels, & no lift (currently) & avg'd over 20mpg on a recent 600 mi. road-trip. mostly freeway, but some hills & in-town. i haven't cracked open the diff's (30/35), but it's marked 3.55. put 87 octane (i know i should use 89 or 91) + lucas fuel treatment in before trip, fresh oil change & running cool as the other side of the pillow (never over 210).
i'm planning a 4.5" lift soon, so i'm watching this one!