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Pros and Cons of 30" or 31"

N

Newbiejeepster

NAXJA Forum User
Location
Akron, Ohio
Ok I have done a bunch of searching but I am undecided and still don't have an exact answer. What are the pros and cons of 30" vs 31" tire? I put on a 3" lift and still have stock wheels on. I want 30 or 31......are there a difference between the two sizes? Is there really much of a size difference with that 1"? I want to use stock rim and go with a mud terrain tire. Is the only difference between the two tires stuffing and a little rubbing issues with the 31's? I am not so sure I really want to start hacking up my body just yet. Parents and fiance will throw a fit since I just bought the XJ. They already threw a fit with the lift kit, you know "it looked good the way it was why did you go and do that!" HAHA So I probably just answered my own question that I should go with 30's I was thinking either goodyear mudders or BFG mudders. If someone can help me out and give me some advice about the two different sizes in tires, i'd appreciate it very much! I'll try to get some pictures in here so you guys can get a visual.
 
3 inches and 31s looks and works good. You will only get the slightest rubbing at full stuff and you dont have to trim anything. If your really worried about rubbing get better bumpstops. I would definately put my vote in for 31s.
 
I went with 31" BFG MT with a 3" lift and had no troubles on factory steel spoke rims and I wheeled the snot out of it. Stick with a 10.5" wide tire or narrower. It may rub the lower rear part of the fender flare with 31's at full lock and stuff. It really just depends on how you drive off road.
 
javik said:
you dont have to trim anything.
Click to expand...

:roflmao:

You will still want to trim. If you don't your tires will make their own room.

I run 3" with 31s and on stock rims, I needed to add 2 washers behind the steering stops on each side. I also had to cut off the front half of the fender at the bumper line and a some cutting and a lot of BFH work on the rear half. I also added 2 hockey pucks to each lower bumpstop cup inside the spring mount.

Someone who didn't know what they were looking at would never suspect they were cut, but you will need to make room for 31s at 3".

It's not bad when you are flexed up going straight, but turn to full lock with one stuffed and the other dropped out and you will rub everywhere without proper trimming and bumpstopping and addressing the steering stops/backspacing. Who goes in a straight line anyway.
 
Go with the 31's.
If you don't you'll wish you would have.
I wish I would have.
30's just don't cut it.
There were several times at WF where I believe that if I had been
running 31's, I would have cleared the obstacle.
 
i'd have to say 30x9.50s.
a 9.50 tire on a stock 7 inch wide rim with stock backspacing won't rub. if it does, it'll be a tiny bit on the LCAs or the sway bar where it bends. that's only with some 9.50 tires i hear. i run 30 inch goodyear MTRs and havn't had any contact with the LCAs yet.
with 30s you've got more power than 31s, better fuel economy, and you don't have to mess around with stuff such as steering stops, bumpstops, and trimming. also, 30s are allways cheaper than 31s.
30s are lighter than 31s. a lighter tire will stop better/faster than a heavier tire. the performance of your braking system may be something to keep in mind if this is going to be your daily driver.
i went with 30s because i'm never going to trim and i'm never going to go over 2 inches. i wheeled it in its stock form for a little over 5 years. 30s are just great compared to stock size. more than plenty for me.
if you think in the future that you'll be going higher, like to a 4.5in lift or something, i'd say get 31s now, but if you're done lifting this truck, i'd at least consider 30s.
 
Last edited:
I ran 31's on my XJ and MJ with no trimming, I did have a 4.5" lift, but they didn't rub even at full stuff. The only rub was on the lower control arm a little and that was a minor adjustment to the stops with a washer... Otherwise perfect... I am now running 32" MTR's on the XJ and only had to do minor trimming to the front of the inner fender, but you have to look close to see it.... My vote would be for 31's....
 
This fella is the most 'high speed, low drag' guy ever when it comes to tires on a somewhat stock XJ. He says you can run 31/10.5's on a stock jeep with a few modifacations to bumpstops, steering stops, and maybe a minor lift (1.5-2"). I will be doing this in the next few months, along with adding some rusty's offroad fenders (as long as I have the cash) and putting in a dakota or grand cherokee leafs and coil spacers. I plan on trimming allot after I add the new fenders. I deliver pizzas and tend to drive with a lead foot, so I am trying to make my jeep offroad capable without jacking it up too much. I'd personally reconstruct the wheel wells before putting on a large lift. This is for personal preferance... I like speed offroad instead of being capable of rock crawling, which I never intend to do much of. Oh yeah, also my "I'm so cheap I don't mind surviving on PB&J just so I can save money on food" mentality makes this frugal approach look pretty good.
 
what is the difference in size between the stock tirs 225/70/15 or whatever they are and 30"? Is there much of a difference at all? I suck on judging tire sizes!! :p Anyone have pictures of stock next to a 30" or 31"?
 
I don't have a picture, but the stock tires are a 28", so figure 1" taller at the axle with a 30"... The tire is 2" taller overall, but only half of that is from the axle to the ground, the other half is above the axle to the top of the tire... So if you take your factory tires and measure 1" all the way around, that will give you an idea how much clearance you will have with a 30", then measure 1.5" and that would be with a 31".
 
With 3" of lift and 31s, you should be just fine. This is a pic of 2" and 31s (true-to-size 31s):

270_7058.jpg


No rubbing yet, as long as I don't turn to full lock (I will be trimming my fenders when my tow hooks and sway bar discos arrive).
 
I was running 31`s on my 95 with a poor man lift and stock steel spoke type rims. The rears rubbed something feirce under full compression on the inner fender wells on flat ground. The fronts rubbed on the LCA`s, and sway bars.
Just annoying if anything. Time for a another 3" of lift.
 
People always say "go up" when you start rubbing but the truth is that if your suspension is working unrestricted, you could have 5" of lift and still rub 31s if you dont address the bumpstops.
Anyways, there really are only two good things about running 31s over 30s: They look better and they have slightly better for off road clearance and traction (in most situations). Other than those issues, the 30s will work better, probably not a great deal better though.
 
Its always the same answer here.... lift/trim it till it doesnt rub. Most folks dont mention bumpstops (why? dont know). You need to bumpstop and/or trim accordingly anytime you are increasing your tire diameter. Of course you will only be able to fit what physically fits in the wheelwell. A 31 fits in the wheelwell so you should be ok in this case.
 
fordtech said:
Its always the same answer here.... lift/trim it till it doesnt rub. Most folks dont mention bumpstops (why? dont know). You need to bumpstop and/or trim accordingly anytime you are increasing your tire diameter. Of course you will only be able to fit what physically fits in the wheelwell. A 31 fits in the wheelwell so you should be ok in this case.
Click to expand...

HA!! beat you to it.
 
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