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Topic Review (Newest First)
05-02-2013 12:11 AM
st1264
Quote:
Originally Posted by paulandrewm View Post
This is what I just received from BFG:
Our information shows the OE tire size was P255/70R18.
For tire size LT285/70R17 LRE, we recommend 45 psi.
Remember to check the psi when the tires are cold. We appreciate your business and thank you for choosing BFGoodrich.
Really? Wow...
04-18-2013 08:22 PM
paulandrewm This is what I just received from BFG:

Our information shows the OE tire size was P255/70R18.

For tire size LT285/70R17 LRE, we recommend 45 psi.

Remember to check the psi when the tires are cold.

We appreciate your business and thank you for choosing BFGoodrich.
04-14-2013 01:59 PM
ahsumtoy
Same Tires

Quote:
Originally Posted by Patrick Molloy View Post
My BFG 33" MUDs run at 33psi all seasons....snow, sand, mud, motorway.
No issues. I get 50,000 miles out of them too. 2003 TJ Rubicon


Sent from my iPad using Tapatalk HD
I have the same exact tires, just put them on and I reduced the PSI from 65psi to 33psi today. Thanks to the Jeep Forum.
04-14-2013 11:20 AM
kbwwolf Y'all are making this more confusing than it should be. Simply put, the figures I gave above for 33" and 35" tires are starting points.

The 31 PSI I run in my tires is based on maximizing tire life, not on squeezing out mileage. And I'm actually on the high side, as far as 35" tires go. If you want better mileage, run a higher PSI. But your tires may not last as long.

Individual preference plays a part, and everybody's Jeep is gonna be different in how it responds to specific tire pressures. Tire brand, class, Jeep weight and driving style are all factors.

If you wanna maximize the lift of your $200 tires, do a chalk test. After that, you might wanna go a little higher or a little lower, depending on how your rig handles at speed on the highway.
04-14-2013 09:07 AM
Rubicondon53 I maintain Yes,^ my BFG KM 2s E rated were wearing badly at 28 lbs... I have them back up to 36 lbs,
04-14-2013 08:53 AM
paulandrewm ^

After more reading, I'm wondering if this is meant for vehicles that require an "E" rated tire as standard equipment. In other words, vehicles of a certain weight require an "E" rated tire as standard and for those vehicles the pressure should not fall below 46 psi.

However, our Jeeps are much lighter. So, when we increase the load capability of the tire we aren't also increasing the load requirements of the vehicle. At this point, wouldn't it make sense that we can run a pressure closer to that required by the vehicle itself?

My question would be: does an "E" rated tire have to be run at a higher pressure than a "C" rated tire all other things being equal?
04-14-2013 08:20 AM
paulandrewm Further to my email above, here's the link to the NHTSA ruling regarding tire pressure. It indicates that for "E" rated tires, the TPMS must activate when the pressure falls below 46 psi!

NPRM on TIRE PRESSURE MONITORING SYSTEM FMVSS No. 138
04-14-2013 08:16 AM
HK_Runner Good points made. It's too bad there are not more C-rated tires in these sizes. Running E-rated tires on a light vehicle is such a bad mismatch.
04-14-2013 07:59 AM
paulandrewm Wow, this is not easy. Other than the wheels, my Jeep is stock weight. Right now my Jeep is being used as a DD on regular (though snow covered) roads.

It looks like kjeeper10 and kbwwolf are running "E" rated. kjeeper10 says 28 and kbwwolf is saying 31.

I hadn't heard the general rule about 33" aftermarket tires being 30-32. I'll probably start at 32" and work my way down.

The concern I had was that some were saying that because "E" rated tires had tougher sidewalls, the pressure should be lower than a "C" to improve ride.

On the other hand, I read on a bunch of FJ forums that Toyota had sent a recall notice to owners of the Trail Teams Edition (which apparently came with "E" rated tires) because they were being run at around 35 psi and at that speed the "E" rated tires became dangerous at speed. The recall changed the TPMS to be higher. Here's a summary:

This Campaign covers back to 2008 and goes through 2011.

FWIW, NHTSA has used information from tire experts to determine the Floor PSI for "E" rated tires. Tests Have confirmed that under-inflating these tires and running at highway speeds WILL cause failure! The will overheat and deform and the sidewall may also separate.

NHTSA has concluded that "E" rated tires should be higher than normal tires and concluded that 46psi or 58% of the max load psi should be used.
04-13-2013 05:34 PM
kjeeper10 315/75/16 "E" Hankook's @ 28 psi
04-13-2013 04:49 PM
Patrick Molloy My BFG 33" MUDs run at 33psi all seasons....snow, sand, mud, motorway.
No issues. I get 50,000 miles out of them too. 2003 TJ Rubicon


Sent from my iPad using Tapatalk HD
04-13-2013 04:47 PM
kbwwolf
Quote:
Originally Posted by paulandrewm View Post
Folks, need some help setting a tire pressure. And before you all yell "Chalk Test!", please understand that I'm in rural Canada and snow is covering all the roads. So, until I can do this in the summer I'm hoping something can give me a little bit of wisdom.

I have a 2012 JKU Sahara. I took off the stock wheels and replaced them with AEV Savegres and a set of "E" rated BFG T/A KOs in 285/70/17.

I called BFG and the phone system has a tire pressure question option for those running different tires than stock. When I got through to a person, she indicated she couldn't provide any help since the tires are bigger than stock. She told me to call Chrysler.

I called Chrysler and... well, let's just say he didn't even know what I meant by "E" rated tires.

I keep reading conflicting information about the correct psi for "E" rated. Any help would be greatly appreciated. And no, I'm not trading them in for "D" or "C" rated...
Unfortunately, it's not a simple answer. How much does your Jeep weigh? What kind of driving do you do? Lots of other variables...

As far as E-rated tires, I'm running 35" GY DuraTracs, and use 31 PSI for optimum tire wear and handling. You'll find that a lot of tire shops, as well as dealerships, will jack your tires up to 36 PSI, as per the door placard on your Jeep, which pertains to the stock SRAs. Way too high.

As a general guide, for 33" aftermarket tires you should be at 30-32 PSI. For 35s, 28-30 PSI. Adjust according to your rig's weight and tire brand.

I've done this in unbroken snow, by the way. It's not as precise as a chalk test on dry tires or ground, but you can estimate your tread depth in snow, and tell – roughly, anyway – how much tread coverage you're getting.

Give it a try.

In the meantime, adjust your tire PSI to the #'s above, and you should be close.
04-13-2013 03:55 PM
HK_Runner On my C-rated 255/75/17 KMs, I ran 32 psi. They have worn perfectly. I just put on 25" MTR Kevlars, and will run 32 PSI. I am C-rated there too. With E-rated tires, I would certainly not go over 32-34. I say set it at 32 and see how they feel. Like I said, at 32, my KMs have worn perfectly, according to my eyes and the guys at the tire shop yesterday.
04-13-2013 03:21 PM
Rubicondon53 I have been running 34 to 36 lbs for nearly 30 years in all my off road oversized tires.. Last year I made a mistake and followed some advise from some folks on these forums and ran 26 to 28 lbs.. Unfortunately every one of my KM2s (255/85/16), have worn prematurely on the (all four) inside edges.. I'm back up to 36 lbs hoping they will wear evenly again.. A costly blunder...
04-13-2013 03:20 PM
whiteyjfm I am not 100% sure, but if it was me, I would do 27 to 30psi.
04-13-2013 02:52 PM
paulandrewm
Tire pressure help! aka BFG are idiots

Folks, need some help setting a tire pressure. And before you all yell "Chalk Test!", please understand that I'm in rural Canada and snow is covering all the roads. So, until I can do this in the summer I'm hoping something can give me a little bit of wisdom.

I have a 2012 JKU Sahara. I took off the stock wheels and replaced them with AEV Savegres and a set of "E" rated BFG T/A KOs in 285/70/17.

I called BFG and the phone system has a tire pressure question option for those running different tires than stock. When I got through to a person, she indicated she couldn't provide any help since the tires are bigger than stock. She told me to call Chrysler.

I called Chrysler and... well, let's just say he didn't even know what I meant by "E" rated tires.

I keep reading conflicting information about the correct psi for "E" rated. Any help would be greatly appreciated. And no, I'm not trading them in for "D" or "C" rated...

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