30x9.50 versus 235/75

[Jarlaxle]

Getting a 1997 Sport, 4.0/auto/231...it will be a commuter, so keeping things mild. It currently has 3/4-worn "American Prospector SUV" tires on it, size 225/75R15, on stock 7" wide 5-spoke steel wheels. Question is basically this: will 30x9.50R15 tires fit a stock XJ? They should...from what I have seen, they're less than an inch taller than a 235/75R15. So...30's on a stock Cherokee, yes or no?

[4.3LXJ]

Yes

[XJMJeep]

Yes!
31's is an option too.
I've seen up to 33's on stock wheels all though I wouldn't recommend it.

[702XJCruiser]

I run 30's and get around pretty good on them.

[bluedragon436]

Yes.. I had 30's on my XJ when I first got it.. and had no binding or other issues on it.. even with playing a little bit offroad..

[dagr8tim]

30's no problem with no trimming.

[Jarlaxle]

What affect (if any) will this have on mileage? This being a commuter that will see 400-450 miles per week, that's important.

[4.3LXJ]

Generally taller tires will reduce milage unless you regear.

[702XJCruiser]

I get 15-16 mpg average regardless of highway or city. Where I'm at there's lot's of uphill grades that go on for as long as the eye can see.

I don't know if it's my motor being weak "last I checked I had about 140 psi compression in each cylinder so probably not" or if it's the 3.55's with 30's but cruising uphill on my way home at 45mph I shift the aw4 into 3rd and it sits at 2000rpm rather than lugging it at 1500 or so. Going up mountain passes I have to shift into 3rd as well or else I can't maintain highway speeds.

On level ground she remains peppy, but hills suck a little bit.

I'd still do the 30's and it's not so bad that I wouldn't consider 31's as far as driveability is concerned.

[dagr8tim]

Columbus is completely flat. I noticed a slight increase in fuel mileage when I went from 225's to 235's.

My only guess is that the larger tires go farther on a single revolution. I did notice my engine turns at a lower speed while cruising.

[702XJCruiser]

I had a 92 Toyota pickup 22re motor 5 speed trans 33"x12.5" on stock gears and it got great mpg's.

[prcjeep]

I put 30's on mine when I got her, ran them til the tread was gone... Only fitment problem was that when turned all the way you will rub on either your front skid plate, or lca. Add a couple of washers behind the turn stop and problem solved...
MPG for me only dropped about 1.5...

Now if you're thinking of 31x10.50's... I originally bought these but after two days took them back and put 30x9.50... My 96 had pretty saggy rear leafs in her and the 31's rubbed the rear fender on just about every bump when drivin down the road. Steering from stop to stop in the front will also cause some additional rubbing where stated above

[Jarlaxle]

What size did the 30's replace? I don't want a 1.5MPG drop if I can help it!

[bluedragon436]

I went from factory size tires to the 30's on mine.. and really didn't notice much if any real drop in MPG.. Even if you only loose 1.5MPG, that really isn't too bad... I'll trade that loss of MPG that you would get from that setup.. to the loss in MPG I have running 33's, w/ 3.55's!! LOL..

[4.3LXJ]

What size did the 30's replace? I don't want a 1.5MPG drop if I can help it!

Anytime you put taller tires on you pay a milage game. The taller you go, the more milage you loose. That is until you regear. The factory geared the vehicle to get the best milage possible and still retain some performance. When you go and change the tire size, you affect the amount of torque required to maintain speed. So the milage changes. It would also change if you put on a smaller tire.

[Jarlaxle]

Depends on the vehicle...I have seen mileage gains from taller tires, due to lower RPM on the highway. Considering the small difference in diameter comparing a 225/75R15 and a 30x9.50 (less than an inch), I suspect the WIDTH is responsible for more of a drop than the height.

[XJMJeep]

I can't speak for the 30's but I'm running 235 75 R15 on my MJ (4.0 / AW4/ 4wd) & get 16-17mpg consistently.
They are a semi aggressive AT ( Goodyear Duratrac's )
I can't imagine 30's being too far off that

[prcjeep]

What size did the 30's replace? I don't want a 1.5MPG drop if I can help it!

They replaced 235x70 or 235x75 I believe... I now get about 12-13 average with 33x1250's on mine with the AX15 tranny and 3.07 stock gearing

[xjrev10]

245/75/16s.

Right around 30, 31 inches.

Stock Xj.

http://img.tapatalk.com/c6e4e19e-800a-6db6.jpg

[Jarlaxle]

Do they hit? Those look awfully close to the fenders in back and the control arms in front.

[uberxj92]

i have a 92 daily driver & i got good mileage on my 31's when i had them until i had to negotiate a long hill or had a trailer on. i have 33's on here now & 3.73 gears now. no problems & mileage is about 14-15 in town & almost 19-20 highway ( 65mph).