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Discussion Starter #1
What do you inflate your ten ply KO2s to? Long story short, my local Costco tire center guy said the KO2s ten ply is supposed to be inflated to 50 psi, but the FJ calls for @ 32-36 = if you only inflate to the FJ spec, the sidewalls give out or something like that? Or something happens with the bead/s? Everyone raves about the KO2s, but why buy them if this happens? After checking out Tire Rack's On-/Off-Road All-Terrain Ratings chart and reading numerous compliments about the tire, I am strongly leaning toward the Cooper Discoverer AT3 4S. Thanks for your two cents.
 

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I have 285/70/17s on the stock alloys and was inflating them around 38 psi (40 was recommended by Discount Tire, but the ride felt a little stiff for me). I now have about 69k miles on them (about ready for some new ones) and have them at 35 since they’re more worn down, which was also recommended last time I had them rotated.
 

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I would just stick to what the FJ says to do, in that 32-36 psi range. I have these tires and I just run them at what the TPMS sensor wants me to run them at.
 

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Just a clarification, the 'E' load range KO2s are not actually 10 ply tires, they have a '10 ply rating', which means they have a load rating that is equivalent to an ancient 10-ply bias-construction tire.

I believe the 'D' and 'E' range KO2s have 5 actual plies in the tread, and are one of the few all-terrain tires with 3-ply sidewalls. 'C' range KO2s have 2-ply sidewalls.

The 32-36 PSI recommendation on the FJ tire inflation label was only applicable to models that were originally delivered with low-pressure 'all-season' street tires. Models delivered with the optional BFG KO-series all-terrain tires got a different tire pressure label with higher inflation pressure (47 PSI), and a different trigger point for the TPMS warning.

If you install 'E' load range tires that have an 80 PSI max inflation pressure, they will be seriously underinflated if you try to run them at 32 PSI.

I run 'E' load range KO2s on my '14, 265/75R16, and usually run them at 45 PSI on the highway and 18-20 PSI off-road. 45 PSI offroad is impossibly brutal, while 18-20 PSI is pretty plush.

After 5 years of running the KO2s, I am totally satisfied with them. Great traction in sand, snow, gravel, wet slippery rock, etc. The only failure was when I got into a thin layer of incredibly greasy adobe clay mud over a hard surface, when they instantly loaded up and turned into tractionless slicks.

No chunking, no problem balancing them, quiet on the highway, and they are wearing perfectly uniformly with rotation every 6K miles.

The '13 and '14 models have a TPMS reset button that allows the owner to set the TPMS setpoint to whatever tire inflation pressure is desired.

The KO2s are extremely popular among the off-road set, for good reason. Remember that for every person who posts a negative review on Tire Rack, there are probably 100+ totally satisfied users who don't feel any urgency to post a positive review. If you read the reviews carefully, you'll find that many were posted by morons with obvious wheel alignment or suspension problems.
 

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Discussion Starter #6
Just a clarification, the 'E' load range KO2s are not actually 10 ply tires, they have a '10 ply rating', which means they have a load rating that is equivalent to an ancient 10-ply bias-construction tire.

I believe the 'D' and 'E' range KO2s have 5 actual plies in the tread, and are one of the few all-terrain tires with 3-ply sidewalls. 'C' range KO2s have 2-ply sidewalls.

The 32-36 PSI recommendation on the FJ tire inflation label was only applicable to models that were originally delivered with low-pressure 'all-season' street tires. Models delivered with the optional BFG KO-series all-terrain tires got a different tire pressure label with higher inflation pressure (47 PSI), and a different trigger point to the TPMS warning.

If you install 'E' load range tires with 80 PSI max inflation pressure, they will be seriously underinflated at 32 PSI.

I run 'E' load range KO2s on my '14, 265/75R16, and usually run them at 45 PSI on the highway and 18-20 PSI off-road. 45 PSI offroad is impossibly brutal, while 18-20 PSI is pretty plush.

After 5 years of running the KO2s, I am totally satisfied with them. Great traction in sand, snow, gravel, wet slippery rock, etc. The only failure was when I got into a thin layer of incredibly greasy adobe clay mud over a hard surface, when they instantly loaded up and turned into tractionless slicks.

No chunking, no problem balancing them, quiet on the highway, and they are wearing perfectly uniformly with rotation every 6K miles.

The '13 and '14 models have a TPMS reset button that allows the owner to set the TPMS setpoint to whatever tire inflation pressure is desired.

The KO2s are extremely popular among the off-road set, for good reason. Remember that for every person who posts a negative review on Tire Rack, there are probably 100+ totally satisfied users who don't feel any urgency to post a positive review. If you read the reviews carefully, you'll find that many were posted by morons with obvious wheel alignment or suspension problems.
Wow- thanks so much for all that detailed info; it certainly helps.
 
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Try this calculator:


Lots of stuff on the site is actually very informative.
 

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Try this calculator:


Lots of stuff on the site is actually very informative.
That's a very useful calculator, taking all the factors into consideration when switching tire size, construction, load rating, etc.
 

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Just keep in mind if you have tires that are too stiff for the weight of your vehicle you may have issues with traction control, vehicle stability control and the brake assist feature.

On the roads around here my sweet spot for summer driving is around 38.

In the winter with even more ruts, etc I keep them down closer to 30.... which I put back up closer to 38 if I go on a big highway drive.

Some members on this forum have MUCH nicer roads and warmer temperatures and can get away with pressures 45 and over... but with my FJ here it gets way too bouncy and I start having traction issues. The last thing you need is for the brakes to lock up on you as you go over a set of railroad tracks or something...

Start with 36 and go from there. If you can put a higher pressure in and not feel like you're going to need to see the dentist after a month of driving like that and/or you are not having issues with the traction and braking system then put more pressure in at small increments.
 

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Just keep in mind if you have tires that are too stiff for the weight of your vehicle you may have issues with traction control, vehicle stability control and the brake assist feature.

On the roads around here my sweet spot for summer driving is around 38.

In the winter with even more ruts, etc I keep them down closer to 30.... which I put back up closer to 38 if I go on a big highway drive.

Some members on this forum have MUCH nicer roads and warmer temperatures and can get away with pressures 45 and over... but with my FJ here it gets way too bouncy and I start having traction issues. The last thing you need is for the brakes to lock up on you as you go over a set of railroad tracks or something...

Start with 36 and go from there. If you can put a higher pressure in and not feel like you're going to need to see the dentist after a month of driving like that and/or you are not having issues with the traction and braking system then put more pressure in at small increments.

Railroad tracks? In Winnipeg?

I agree with winter on this.

Surprised no one has mentioned "The Chalk Test"
 
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FWIW, my 2013 TTSE came stock with BFG 275-75/16 KO's and the pressure rating inside my door is 46psi. I ran on those for 90k miles at 45psi and JUST replaced them (literally 2 days ago) with KO2's. That ran great, and wore evenly at 45psi, and still passed inspection earlier this year -- they've been absolutely incredible. I do about 99% of driving on the road, though, and my FJ is my daily driver, too. Some snow/ice driving in the New England winters, and maybe 3-5 times a year on sand.

I just checked my new KO2's this morning, and my mechanic set them at 35psi. I called him just about an hour ago to ask why. He said "Oh, you don't want to run them at 45. 35 is much better for these tires" ... ??? Yeah, no. I'm gonna run them at my usual 45 PSI, which gets me almost 20mpg on the highway. He even sent me an excerpt from alldata that shows a ~36psi recommendation. I think he was looking at the non-TTSE recommendations, though. I don't think the KO2's are so significantly different than the original KO's that I would want to run them at a different PSI. Especially when most of my driving is road/highway, and I had such a great run with the KO's.

If I was doing a lot more dirt road or off-road driving, I might run them at a lower PSI.
 

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Railroad tracks? In Winnipeg?

I agree with winter on this.

Surprised no one has mentioned "The Chalk Test"
The chalk test is really intended for vehicles running tires that have load ratings that are fairly closely matched to the vehicle's actual weight, to achieve the best possible traction on paved surfaces. It works great for performance street cars.

However, for many/most off-road vehicles, people install larger/heavier than 'stock' (or much larger/much-heavier than stock), tires for improved flotation in sand, increased ground clearance, increased sidewall resistance to puncture, 'bad-ass' appearance, etc.

In these cases, there is frequently a large mis-match between the tire's load rating and the vehicle's actual weight. Performing a chalk test may end up indicating that a very low (unsafe for several reasons) pressure is required to achieve full-width contact on a hard, flat surface.

So you end up with an inflation pressure that looks too high per the chalk test, but is necessary to keep the tire at a 'safe' working pressure. The drawbacks? Stiff ride on the street, reduced 'ultimate' cornering power in a skid-pad test, possibly a little greater wear in the center of the tire, etc.

Otherwise, go back to exactly the same size and load rating tire that the vehicle was delivered with.
 

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Yeah, the face of my tires are pretty flat.... I don't have a pile of confidence in the chalk test in my situation with the E rated duratracs.
I go by feel moreso....
 

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Discussion Starter #15
I appreciate all the comments, advice, and general info. I went with the Cooper Discoverer AT3 4S tires.

1139579
 
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