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post #1 of (permalink) Old 07-30-2002, 12:35 PM
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Tires...?

Hey guys, once again a relatively newbie here, lookin' to put some 31" on my TJ - any recommendations? With stock wheels what's the widest you can go? Thanks so much, as always!

Ashley
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post #2 of (permalink) Old 07-30-2002, 03:10 PM
 
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Re: Tires...?

Ashley, you have asked the eternal jeep question. Tire choice depends on a lot of things

1. The type of wheeling you do.
2. How often you wheel.
3. How is your jeep set up
etc. etc.

I see you are in PA, I don't know the area, but from what I hear there is a fair bit of mud, and not a whole lot of rocks. I am assuming you are using your Jeep as your daily driver still, so really agressive tires probably are out of the question. For that type of terrain I would recommend the Goodyear MT/R's, that's what I use, not really loud on the road, great off-road traction, stiff sidewall, runs great at low pressure.

I know a lot of guys/gals use the BFG Mud-Terrain, and for a good all round tire, try the BFG All-Terrain.

As far as width, that can be a little tricky. If you Jeep still has the wheels in the picture on your website, then I don't know if any of the above tires would fit, those rims look awfully thin. If you can find out how wide those rims are (I'm assuming the are 15" diameter), then you can use this chart to determine what fits(for the MT/R's)

www.bfgoodrichtires.com

Keep in mind that although 31" tires fit under a TJ, you might have slight rubbing on the control arms or other suspension parts when you turn your steering wheel to full lock. I do, but it isn't enough to worry about.

Hope this helps

Rob
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post #3 of (permalink) Old 07-30-2002, 03:55 PM
Yukonart
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Re: Tires...?

First off, welcome to the forum, Ashley. . . . good to see another fem up here. . . need more of ya in our ranks!

Yup, those stock steel rims are a bit thin for decent 31's. They should be 15x7's at the widest. If you're going to run 31's, I think you'll need at least another inch in rim width to accommodate them. Might want to see if anyone has some stock Sport or Saraha rims they're willing to sell from the large tire and wheel package they got with their Jeep. Those should be 15x8's. With those, you should be able to fit up to 31's or so.

I'm no Jeep expert (working on that) but I do know my tire and wheel specs. Right now you're at about 27" Upgrading to 31's should yield you about 2" in additional ground clearance, but as was mentioned, you should be aware of potential, if not expected, rubbing on your suspension and steering components unless you opt for a suspension upgrade of some kind. In this case, unless you're going off-road a lot, you may want to stick with no larger than 30's and make sure the width is such that you won't experience much, if any, rubbing when turning sharply.

The tire/wheel gambit is a fun one to play if you know the math involved. [img]images/icons/smile.gif[/img]

You should have:
205/75-15 tires
205 tread width in milimeters. . . divide by 25.5 (or so) to get inches. . . about 8"
75 is your sidewall aspect ratio. . . 75% of your tread width. . . about 6"
15 represents your wheel diameter. . . . 15"

Overall tire/wheel rolling diameter can be figured this way:
Tread width / 25.5 x Aspect ratio (in percent) x 2 (because sidewall appears twice in diameter) + Wheel diameter

205 / 25.5 x .75 x 2 + 15 = 27 inches (Your current rolling diameter)
245 / 25.5 x .75 x 2 + 15 = 29.5 inches. . . almost 30. (Might want to go with those.) I know it's a lot to swallow, but these are the numbers involved.

BTW, this will work for ANY tire and wheel plus-sizing application. For instance: My new Civic. . . .

185/60-15 Stock size. . . . 23.71" rolling diameter
215/40-17 New size . . . . . 23.75" rolling diameter
Exact same equation, different application. In this case, I wanted to PRESERVE my overall rolliing diameter, so the aspect ratio went from 60% to 40%, even though the tires got wider, and the wheels larger, the overall diameter was maintained through the aspect ratio. [img]images/icons/smile.gif[/img] You see? There are MANY practical applications for algebra! SHHHHHHH!!!!!!

lol. . . hope this all helps!
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post #4 of (permalink) Old 07-30-2002, 06:10 PM
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Re: Tires...?

Hey boys, and thanks as always for your responses! I hope that you get around to reading this since I'm just posting it under my original topic (to save a lil space), but here goes:

You both mentioned rubbing on the flares, suspension, etc - I was planning to do a slight lift with coil spacers (any opinions on this?), abot 2.5" or so excluding tires. I mean, come on, I don't want a Rubicon-ready swamper, I still need it to be a daily driver and a little bit femme-chic. [img]images/icons/smile.gif[/img] Kidding (about the last part)!

It kinda bums me out knowing that not only do I have to buy tires but new rims also. How much would the whole deal cost (rims and tires)? I'm on a college-kid budget and every penny I can spare I put into my TJ, but that's usually not enough! You mentioned the stock, used Sport/Sahara rims, where could I get a set of 5 of these? I haven't been very successful in my surfing as far as finding places to buy USED parts.

Oh, and hey, how about a recommended brand for shocks?

*mwah* You guys are the best!

-Ashley- (O)|||(O)

PS. Yukonart, thanks for that math! Now that I know I can apply algebra to my pride and joy, it makes homework a little more exciting. [img]images/icons/smile.gif[/img]
post #5 of (permalink) Old 07-30-2002, 11:23 PM
thejunker
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Re: Tires...?

I run 31's on my XJ with stock tires that are 15x7. Only problems are the fronts hitting the coils at full turn, and I shredded one of my rear fender flares on Behind the Rocks during full compression, due to very soft springs (OME). My winter tires are 31's on 15x8's and they do not rub the coils in front.

I know a TJ is a different beast, but I think you can get by with 31x10.5's on 15x7 wheels, just make sure you have enough clearance or body parts will start bending...
post #6 of (permalink) Old 07-31-2002, 07:48 AM
 
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Re: Tires...?

Sometimes I should read my own advice. Both BFG and Goodyear, say you can mount 10.5" wide tires on a 7" rim. So you don't need new rims.

Coil spacers are a good inexpensive way to lift a jeep. You don't really need that much lift to run 31's. Here's what I'd do, in fact, it's what I did. Get the bigger tires, don't get a lift, spend the extra money that you save either on the tires, or on skid plate protection (oil pan, beefier gas tank skid etc.). Get a set of swaybar quick disconnects, then wheel it. You will be amazed at what these vehicles can do in their "stock form". Get some tow hooks as well, find a local 4wd club, go on some trail runs, make some friends, have fun. Also this way you can get a sense of what you "need" to make the jeep the way you want it.

Rob
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post #7 of (permalink) Old 07-31-2002, 08:24 AM
jersey89yj
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Re: Tires...?

Ashley,

You do not need new rims for a 31" x 10.5" tire. I have been (until recently) been running 31's on my stock 15" x 7" wheels for 9 years. The only problem I had was rubbing the flares and leaf springs (YJ) at full steering lock. I added a 1" body lift to cure the flair rubbing. TJ's should fit 31's with no fender rubbing, but I'm not sure about the control arms. I was able to fit 33's by cutting the sheet metal and putting on TJ flairs (even before i added a 3.5" lift). You should be fine with the 31's.
JT
post #8 of (permalink) Old 07-31-2002, 08:36 AM
thejunker
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Re: Tires...?

<blockquote><font class="small">In reply to:</font><hr>


You will be amazed at what these vehicles can do in their "stock form".


<hr></blockquote>

I second that. I ran my XJ through a bunch of the easier (1 - 2.5 rated) trails (in Moab) with my stock everything (including wimpy 235/65 tires), after I put on the lift and 31's, I was able to do all but the most hardcore trails, and even some sections of those.

I learned how to drive off-road this way, with careful attention and prescision. I had had my share of body damage because the tires are still on the small side (combined with the longer wheelbase of the XJ), but I am confident now and have good experience.

I am now working on a CJ and it will be much more capable off-road, but I am glad I learned on a close to stock vehicle because it taught me what I needed, how to drive, how to spot, etc.

Have fun Jeepin!

--pm
post #9 of (permalink) Old 07-31-2002, 09:06 AM
 
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Re: Tires...?

You can run a 31 x 10.5 on a TJ with stock rims. I'd go with a 2" coil spacer cause although you can fit the 31 x 10.5 under the Jeep IMO it looks a lil strange cause you fill up so much of the fenderwell. And with sway bar disco'd you will rub if you don't add a few inches. You can keep you stock shocks, run the 2" coil spacer, run 31 x 10.5 and you'll be lookin good while riding high and mighty.

Now if I couldn't only convince my lil sister to do stuff like this to her Jeep we'd be in business. Because of the school she goes into she is swayed by a more thuggish type crowd and doens't wanna do the good thing to her Jeep.
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post #10 of (permalink) Old 07-31-2002, 06:30 PM
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Re: Tires...?

You guys are THE BEST! [img]images/icons/smile.gif[/img] Thanks for your advice, as usual! Can't wait to try out all your suggestions. Ridin' high and mighty...*grin*

Love,
Ashley
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