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Max Tire HEIGHT, with stock lift & 235/85 wheels? PICS!!
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=8&t=25163		 Page 1 of 3
Author:  geordi [ Mon Oct 08, 2007 12:37 am ]
Post subject:  Max Tire HEIGHT, with stock lift & 235/85 wheels? PICS!!
Ok, I've seen a lot of comments and charts on here, but I'm not really sure what people are describing as "rubbing" on these wheels.

Here is what I'm looking at:

http://www.tirerack.com/tires/tires.jsp?tireMake=BFGoodrich&tireModel=Commercial+T%2FA+All-Season&partnum=385R6COMMTA&vehicleSearch=false&fromCompare1=yes&place=0

And here are the exact specs on that tire:

235/85R16
Load Index 120 = 3169lbs (1440kg) per tire
Load Index 116 = 2806lbs ( 1275kg) per tire
Speed Rating “Q” = 99mph (160kph) 120/116Q E

Max load: 3042 lbs.
Max pressure: 80 psi
Tread Depth: 15/32"
Weight: 45 lbs.
Rim Width Range: 6-7"
Measured Rim Width: 6.5"
Section Width: 9.3"
Overall Diam: 31.4"
RPM per mile: 662

So... The real question is - WHERE is it going to rub on? A weld at the back of the wheel well? The plastic fender skirt?

I'm not really concerned with rock crawling or off roading, but I do get some pothole bounces in my driving, and do a lot of highway driving. So will these fit without ripping off the fender skirts?

Thanks muchly for the info, these tires are expensive to try and buy sight un-seen...
Author:  corwyyn [ Mon Oct 08, 2007 12:44 am ]
Post subject: 
Two places they are guaranteed to rub on a stock height KJ:

1) The front of the wheel well, where the access door is for the fog lights on the '02-04 models. '05+ it's just one piece IIRC.
2) The pinch weld. Look in the back of your front wheel wells, there is a triangular plastic piece that sticks out on the bottom. Under that is a section of the pinch weld. You'll need to remove the plastic and hammer down the pinch weld, then either paint the metal or close up the plastic again.

Since they're a 235 you shouldn't have any other problems, no rubbing on the control arms or anything like that although you may rub the top of the wheel well if you hit a good bump (but it would have to be a GOOD bump).
Author:  geordi [ Mon Oct 08, 2007 1:07 am ]
Post subject: 
I have an 05 CRD... If I don't have the fogs (I don't) and if that area at the front is all one piece... Will it still rub there? I'm willing to consider a small lift, if it can be done without a huge amount of effort and expense. Maybe some spring / strut spacer pads or something?
Author:  tommudd [ Mon Oct 08, 2007 12:02 pm ]
Post subject: 
yes you will need a lift you can run 245-70 X16s with no lift and not much trouble at all but they are about 29.5 or 29.6 inches tall where you are wanting to go to a 31.4 or5 tall , pound down the pinch weld and start cutting in the front of the tire area
If yore going to do it, do it right with a spring lift will be happier in the end just my 2 cents
Author:  geordi [ Mon Oct 08, 2007 5:15 pm ]
Post subject: 
Well, I just bought 4 BF Goodrich Commercial T/A highway shoes... 215/85/16 LRE 116Q specs, they are 29.5 tall and don't rub anywhere. I had them try a 235/85/16 version of the same tire on the front, and it missed being perfect by *that much* b/c it was squeezing the plastic both front and back when the wheel was turned. It was only getting the plastic a *little* bit... But I just bought the truck, and I'm not about to start carving up the wheel wells quite this soon.

I'll get a lift eventually, and those will be my next tires. In about 50k miles AT LEAST, as these are 80psi load monsters that will probably NEVER be anywhere near their 3800lb capacity. But I've got to air them up a bit more, as at only 40psi they look far too soft and that increased contact patch will make them hot and wear them out. Once they are full... They should last dang near forever.
Author:  Supalive [ Mon Oct 08, 2007 5:24 pm ]
Post subject: 
PICS?
Author:  dieseldoesit [ Tue Oct 09, 2007 12:30 pm ]
Post subject: 
yah, were the pics at?
Author:  geordi [ Tue Oct 09, 2007 4:57 pm ]
Post subject: 
Lol sheesh, tough room. :roll: :lol:

I did take some pics of the too-big tire on there, and I have some pics of the original ones. Let me get a couple of these current ones, and I'll put them all here for posterity.

Buncha Jeep Geeks. :roll:


:lol:
Author:  Jeger [ Tue Oct 09, 2007 6:29 pm ]
Post subject: 
Image

Sorry, just had to throw that one in there 8)

So 215/85-16's EH? And there is no rubbing at all, even with the wheels stuffed? Please sayt its true!

Because that should be a 30" tire at the least. Most are 30.5". I have been waiting to see some pics/proof of these shoes on a kj (especially a CRD :D ) and if they fit with even with a little rubbing I will be getting me some.
Author:  geordi [ Wed Oct 10, 2007 1:53 pm ]
Post subject: 
Pics of the shoes:

Stock tires on the front:

Image

Stock tire on the rear:

Image

235-85-16 on the front, notice the little brown spot just visible on the shoulder of the tread. That (and a matching spot on the front) were where it rubbed, just a little bit.

Image

Now, the unveiling... 215-85-16 on the front:

Image

Rear:

Image

Full view:

Image
Image


So... What's the verdict? They ride nice and quiet, now that they are aired up to 80psi... At the 40psi they left Sams Club with, the ride was just as cushy as on the stock tires, but I didn't like the way they sat on the ground - too much bulge at the bottom, means excess flex and heat and failure. But the ride is not as harsh as I thought it would be, so thats a good thing. The ride is crisp and I feel connected to the road, rather than being jolted like riding in a heavy truck that is unloaded. THAT is a tough ride, you feel EVERY bump. I would suggest these for anyone looking for mileage, and they can haul 2600 lbs EACH, so are more than capable of hauling around our little freight engines.
Author:  tommudd [ Wed Oct 10, 2007 2:53 pm ]
Post subject: 
geordi wrote:
Pics of the shoes:

Stock tires on the front:

Image

Stock tire on the rear:

Image

235-85-16 on the front, notice the little brown spot just visible on the shoulder of the tread. That (and a matching spot on the front) were where it rubbed, just a little bit.

Image

Now, the unveiling... 215-85-16 on the front:

Image

Rear:

Image

Full view:

Image
Image


So... What's the verdict? They ride nice and quiet, now that they are aired up to 80psi... At the 40psi they left Sams Club with, the ride was just as cushy as on the stock tires, but I didn't like the way they sat on the ground - too much bulge at the bottom, means excess flex and heat and failure. But the ride is not as harsh as I thought it would be, so thats a good thing. The ride is crisp and I feel connected to the road, rather than being jolted like riding in a heavy truck that is unloaded. THAT is a tough ride, you feel EVERY bump. I would suggest these for anyone looking for mileage, and they can haul 2600 lbs EACH, so are more than capable of hauling around our little freight engines.


80 lbs of air in the tires all I can say is wow that is a lot! not argiung just saying.....
Author:  geordi [ Wed Oct 10, 2007 3:11 pm ]
Post subject: 
It might seem like that, but these aren't "passenger car" tires, these are commercial grade TRUCK tires. Every bit the same as the 22.5" black monsters that ride under every semi you have ever passed on the road. These are just a little smaller. 80psi is the sidewall max, the 22.5" size are 120psi max usually. What I said in the other thread still stands, with one exception: While you don't want to EVER run a "passenger car" tire less than 10% below the sidewall max, a commercial truck tire has a much stronger sidewall (so it can be re-treaded) and can usually be safely run as much as 30% below the max, weight permitting.

So I could run these potentially at 60psi, and still be 4 psi above that safety threshold. I might do that eventually, if I decide the ride is too stiff or they feel too twitchy at highway speeds. Right now, I want to run a full tank through with them on the KJ, so I can see how much the mileage has changed with these shoes.

If you look at the "front" and "rear" closeups of the new tires, you can see the oversized contact patch created by only 40psi in the tires. Compare that to the picture outside the brick building (so it's on pavement) and look at the difference a full air charge makes.
Author:  tjkj2002 [ Wed Oct 10, 2007 4:27 pm ]
Post subject: 
Quote:
While you don't want to EVER run a "passenger car" tire less than 10% below the sidewall max, a commercial truck tire has a much stronger sidewall (so it can be re-treaded) and can usually be safely run as much as 30% below the max, weight permitting.
Not sure wher you got that info but it is wrong.Consider the stock tires that come on a KJ have a max psi of 44,and according to the manufacture(Chrysler) the tires on a KJ should be at 32psi,that's way more then 10%.As with most vehicles(3/4ton+ excluded) run there tires at more then 10% under the max psi rating of the tires and do it saftley.Heck my 265/75 Trxus MT's (D range) are rated at 65psi max and the best wear and ride for my KJ is 42psi.Wieght has alot to do with the best psi,you will be wearing the center of your tread real fast running at 80psi,it must ride pretty rough too.
Author:  tommudd [ Wed Oct 10, 2007 5:04 pm ]
Post subject: 
I have reread it through 4 times now and still dont get where you come up with the fiqures. I know about truck tires I still hold my CDL and have close to a million miles but you are comparing a vehicle that weighs 30,000 lbs empty 80/85000 fully loaded so a lot of difference. Now if these (your new ones) were on a one ton that pulled a loaded goose neck all the time then yes

But again no arguements just want to see some things to back up your theory of air pressures, just a friendly conversation here
Author:  geordi [ Thu Oct 11, 2007 12:27 am ]
Post subject: 
I guess I'm not really sure where the questions are. If you are talking about the 10% figure, that is what I heard (read) in news reports from the tire makers during the Ford / Firestone lawsuits. I'm sorry they decided not to include those figures in their general FAQs, but I DO distinctly remember Firestone claiming that they had recommended a minimum pressure for the tires they were supplying to Ford (not more than 10% below the sidewall max), and Ford (in it's infinite wisdom greater than the DESIGNER of the product being used) printed a lower number on the door stickers. Stupid customers then didn't bother to maintain even THAT pressure, and the tires did what they do: lost about 1psi / month of operation, dropping FAR below what Firestone had specified.

Does that mean the tires would magically not fail, since the all powerful FORD had decided to "suggest" to the owners a lower pressure than Firestone said? of course not. They failed, peeled off, and people died.

Ford did much the same thing with the Navistar diesel engines from International. International provided the engines with specific maximum RPM and HP guidelines to prevent damage to the engines. Ford (again with the infinite wisdom stuff) tossed the ECMs provided by International, and specced out their own ECM maps with much faster RPMs for normal operations, and higher boost levels to reach more HP at those faster RPM numbers. They did this INSTEAD of installing a transmission with more and lower gearing... Which would have cost more money than swapping a computer out.

The engines started failing right and left, as I'm sure you have heard about in the news.

The point is that the supplier of a specific component has designed that component to work in a variety of conditions, and has specced it out at a certain level according to their design. The OEM is taking that product, and then re-engineering the specs, without complete knowledge of the possible results. The tire specs provided by a CAR maker (not a tire maker) are primarily designed to offer a soft cushy ride to the driver, at the expense of fuel mileage and tire lifespan.

Why would a manufacturer do this? B/c then they DON'T need to put in softer springs ($$) softer shocks ($$) or better engineer the design of the suspension ($$$$). Tires are a wear item, and don't cost the mfgr ANYTHING, as they don't warranty them for any specific lifespan. Ditto for fuel mileage. They would rather save 5 CENTS by not installing a drain plug in a transmission pan, and make the life of a technician that much worse... Because it saves 5 cents per vehicle. If airing-down the tires saves money so they can get away with using cheaper components elsewhere and let the tires absorb the shocks... Think about it.



Sorry for the book, but that sometimes needs to be said, so people think about WHY things are the way they are. Never assume business will "do the right thing" EVER without being forced. Seatbelts used to be an optional feature until the government FORCED the car makers to include them in every car.

On the tire pressure while unloaded, and the wear... I run full sidewall max in all my vehicles. In some cases (the RVs especially) they have tires that are MUCH higher load ranges than what is sitting on them. I have not had one single tire wear in the center, EVER. To me, it's all about controlling the contact patch. The contact patch may not substantially increase to the sides of the tread direction unless the tire is SERIOUSLY underpressured. But if the tire is partially low, the length will increase. With that length comes extra flexing as the round surface must flatten out and then re-curve continually while rotating, AND it is also flexing the shoulders outward as well. Think about those cheese-and-cracker packages we all had as kids. The ones with the red plastic spreader. Did you ever bend them in half to make a warm spot? That's EXACTLY what the tire is doing ALL the time. Modern casings of tires are much stiffer than even just a few years ago. With steel sidewall belts, tire mis-shaping from over inflation is becoming a thing of the past. What happens when the vehicle is unloaded compared to the carrying capacity of that fully-pressured tire? The contact patch will shorten along the tread direction, reducing friction. The steel belts maintain the shape, and the square surface to the road. Much older tires didn't even have steel belts on the tread, and certainly WOULD "balloon" into a rounded shape when lightly loaded or over-pressured. Modern tires don't.

All of this is based on my own experiences with all of the vehicles my family owns, since I am the one that maintains them. As I said, I run them ALL at full sidewall max, and not only do they NOT get center-wear, but I get the FULL mileage out of the tires, even while not rotating them out of position on the car. Your mileage may vary, but this is my story.
Author:  andOrr [ Thu Oct 11, 2007 1:05 am ]
Post subject: 
Just out of curiosity, geordi, what's your wet traction or ice traction like with those high pressures? That would be the determining factor for me. All else equal, I would go for max fuel economy and mileage.
Author:  geordi [ Thu Oct 11, 2007 9:43 am ]
Post subject: 
I don't have any experience with ice and the Liberty yet, but for rain / mud, these seem to be fine. Narrower tires are actually better, as you won't float on top of the mud, but press down into it and find the harder stuff. On ice, the experience I do have is with a 34' RV running on 8R22.5 (IIRC on the size) tires. Those are about equivalent in contact patch and type of tire to these commercial 215/85. I wasn't crazy about driving an 11 ton vehicle across a sheet of ice at a truck stop, but the tires handled fine.
Author:  Pote [ Thu Oct 11, 2007 11:41 am ]
Post subject: 
Keep an eye on that rubbing. It looks like if you go full lock they are really going to bite into those rub spots. On your side view of just the front tire (one with the brown rub spots) it appears there is barely any room and the tires are still straight. while the front plastic is much more forgiving, that pinch weld rub might be a problem waiting to happen. i was just looking at a guys tire that rubbed on the pinch weld...the weld was literally peeling and chipping away his brand new treads. Do you have any pics with the wheels at full turn? Just be weary of the rub at the pinch. His tires that were rubbing the pinch looked awful after a very short time with big hunks and tears out of the treads. ;)
Author:  Jeger [ Thu Oct 11, 2007 12:16 pm ]
Post subject: 
The ones that showed the rub spots were 235/85's. He is now wearing 215/85's and says they dont rub at all.

So still true? No rubbing lock to lock even with the wheels stuffed? I just need to be sure before I spend 500 some odd dollars on new rubber.
Author:  geordi [ Thu Oct 11, 2007 12:53 pm ]
Post subject: 
Jeger is correct, the rub pic was from the 235s, but I don't believe they were getting into the pinch weld, just the plastic cover for it. Either way, I wasn't interested in pulling the cover and pounding on a car I just bought. And the 215s don't seem to be polishing the plastic at all. I'll try to grab a pic of the wheels at lock, for some final clarity.
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