35 should be pretty close. You want to run the right tire pressure so you get a good, even contact patch on the ground. The best way I know is to park on a pretty level street and use a piece of chalk to draw a line across the width of the tires. Then drive in a straight line for at least a few tire revolutions. If the chalk is worn off all the way across, you're at least close. If the chalk wasn't touched on the outsides, your pressure's too high. If it wasn't worn off in the middle, it's too low.

After all that, keep an eye on the wear and same thing applies. More wear on the outside than the center means too low and more wear in the center means too high.

 

They way I understand it, regardless of the load rating, the OEM door jamb psi recommendation supersedes that of the tire manufacturer.

That said, I believe that Toyota recently upped the psi recommendation, and are reprogramming TPMS sensors at 45psi, and I can't confirm because I'm not near vehicle, but after a recent service, I believe they did to mine.

I'm running a BFG AT 10 ply (e) and have experimented with varying tire pressures from 35 to 60, and found ride quality suffered after 45 psi, dramatically, in my opinion.

 

That said, I believe that Toyota recently upped the psi recommendation, and are reprogramming TPMS sensors at 45psi, and I can't confirm because I'm not near vehicle, but after a recent service, I believe they did to mine.

The stock FJ tires aren't rated for pressure that high, they're rated for either 32 or 35 psi.

I run my KM2 255/80/17 (E rated) at 40 psi and haven't had an problem. May try going down to 37, but I've had them for over a year and 40's been good to me.

 

Higher pressure will help gas mileage a little but if your tires wear out too soon it takes away any savings in fuel. The door jamb sticker is a good place to start but an e-rated tire is usually stiffer and may need less pressure to give an even contact patch.

 

I run 32 on road (MTs)

14 to 30 off road

 

I run 42# good contact patch and not to hard.

 

Running 42# as well on 285 KM2's, not too soft but not too hard either.

 

36 psi

 

Running LT285/70R17E Nitto Terra Grapplers.

They feel good and wear nicely at 35PSI. However, on long trips out to Colorado/Utah I often run them closer to 38PSI because I generally have extra weight along and it gives a touch less rolling resistance.

I think I can tell the difference in ride from 35 to 38 as expansion joints are more pronounced. I have driven with them as high as 45PSI and the ride was akin to my old '64 Falcon on narrow bias ply tires. NOT good or safe. Hard tires tend to pull you into "grooves" and offer a little less contact patch.

 

I'm running Nitto Terrain Grapplers LT285/65R18's. Previous FJ wore BFG AT-ko's on Walker-Evans 17" rims. Both with 4" lifts, prev had AllPro UCA's, newer has springs/shock and sway bar shims. Newer FJ has stock UCA's.

1. I've had shake problems with both FJ's, but the Nitto 285's are much worse than the BFG's. Yesterday it was so bad that it actually scared my wife. Didn't do a lot for my confidence, either. That was with 35 psi in all 4.

Today I rotated the Nittos front to back and pushed them to 45 which is what I ran in the BFG's.

Absolute lack of shakehttp://www.fjcruiserforums.com/forums/images/smilies/rocker.gif! The Nitto's would start to shake at about 45 mph and continue all the way to 60 mph. After the rotation and pressure change there is NO shake clear up to 80 mph.

BUT -

Air pressure is critical! Both tires are big (nittos=33", BFG's=35"), both are E-rated and both demand at least 40 psi before the shaking is reduced. These are BIG tires (did I already say that?) and the "factory" spec of 32 psi is not even applicable to them! I guarantee that running much less than 40 psi will contribute to the shake and it was downright scary at 35psi.


Concerning wear - the Nitto's showed inside and outside edge wear which is an indication of under-inflation. That was at 35 lbs. I'll closely monitor them at 45 psi and should know within a couple of weeks what the higher pressure means in terms of even wear, but my experience with the BFG's was that the wear was also better at 45+ psi.

Yeah, the ride is going to be a bit rougher than a nice, soft 30-something psi but what do you expect for a heavy off-road tire? Besides, with the cost of these tires, I'll take a rougher ride and longer life over smooth and short anytime.

FYI, I tow around 3200-3600 lbs of travel trailer, which is what we are living in right now. Haven't towed with the Nitto tires yet but with the BFG tires I always ran 50 to 55 psi rear/48-50 psi front when towing and that worked great. Hope it's the same with the Nittos.

If the problem occurs again, I'll probably spring for new UCA's and the improved suspension geometry they provide but that's a LOT of cash I could use in other places...

 

Run between 38-40psi on the road. Stock-size eload duratracs. If you have freeways with expansion joints, try around 36-38, works for me.

 

2013 TT with BFG 16" E load rated tires has 46 as recommended tire pressure. I have 10k on my truck running at that pressure and tires are wearing evenly, actually hardly any wear at all.

 

My Michelin LTX AT2s run with a Michelin-recommended for the FJ 50 PSI.

 

I run 42psi with my Nitto Trail Grappler.


Sent from AutoGuide.com Free App

 

Likewise.

 

Air pressure is critical! Both tires are big (nittos=33", BFG's=35"), both are E-rated and both demand at least 40 psi before the shaking is reduced. These are BIG tires (did I already say that?) and the "factory" spec of 32 psi is not even applicable to them! I guarantee that running much less than 40 psi will contribute to the shake and it was downright scary at 35psi.

I need to experiment more with trying to reduce my shake through inflation. I'm having a hard time understanding though how increasing tire inflation reduces shake. I would think the opposite might occur, due to the tire being less stiff with lower air pressures, and possibly absorbing more vibrations. Could someone explain to me why this theory is invalid, that is, lower air pressures increasing steering wheel shake? FYI, I run 255/80/17 BFGs too.

 

Stock 2013 TT BFG 265/75R16 E Rated Tires recommends 46 PSI on the door sticker, which seems excessive for the weight of this vehicle (only about 1100 pounds per tire).

Toyota technician recommended 38-40 PSI. I am running at 40 PSI now and have a much smoother ride than at 46 PSI, with a slight radial bulge.

Chalk Test today shows 40 PSI to be too high (wearing 80% center, not on the edges). Will air down to 38 and try again tomorrow.

Interested to see what others have decided based on the chalk test alone.

 

Hate to put words in Smalldog's mouth, but I asked him that question some time ago (at least at that time he was running the same tires as me - BFG 255/80R17s, load range E), and he said 35 lbs. And I believe he obtained that result with the chalk test. Maybe Smalldog can jump in here to confirm or correct me if I got it wrong.

 

TPMS is supposed to be calibrated to come on at 75% of recommended pressure (46 PSI), so for this vehicle and tires, .75 x 46 = 34.5 PSI. I should be OK running 36-38 PSI without the light coming on.

It's not coming on at 40. Will try 38 tomorrow, as the chalk test shows 40 to be a tad too high.

 

So where does 46 PSI come from???

The NHTSA have decided that the magic number 46 PSI is the minimum PSI for ALL E-Rated Tires - Regardless of tire size, vehicle type or vehicle weight. This number is based on 58% of the maximum tire pressure of 80 PSI (.58x80=46.4). I can't find out where they get 58% from. This is the government after all.

This has nothing to do with the weight or type of vehicle, or if the tire is running flat across the center (results of the chalk test), or it's grossly over inflated (like it appears to be on the FJ Cruiser). 46 PSI is 58% of the maximum rating of an E-Rated Tire - that's it.

It you look on any tire manufacture's inflation chart, 46 PSI is recommended for a 10,000 pound vehicle, which is 2x heavier than a stock FJ Cruiser.

TPMS are calibrated to 75% of 46 PSI, or 34.5 PSI. That means if you drop below 34.5 PSI the TPMS light should come on.

Correct me if I'm wrong, (I'm sure someone will), but I would recommend doing the chalk test first, and keep the pressure above 34.5 PSI to keep the TPMS light from coming on. Based on my chalk test today, 40 PSI is a tad too high, so 46 PSI is way out of range. I'm guessing 35-38 PSI (which is also what my dealer recommends) depending on how your FJ Cruiser is loaded.

Maybe if you are carrying around a load of bricks or hauling a very heavy trailer, you might want to bump it back up to 46 PSI.

Will continue chalk testing...

 

I spoke to three different technicians at Michelin, and my tire dealer spoke to them as well

All four sources stated that for their E-rated LTX A/T2 10-ply, used on a Toyota FJ Cruiser, their recommended pressure is 50 PSI.

 

I run my E-rated Cooper STT 295/70/17 at 49.3859 psi. I ran my last set at said psi and got 43K out of them with even wear, smooth ride and they still had about 10/32 left when I replaced them.

 

46-50 PSI basically tosses out any chalk testing.

Running at those higher pressures, the sides of the tires never touch the road, because the FJ Cruiser isn't heavy enough or the tire pressure is too high to make full contact.

The chalk test shows that it's running on the center about 75% of the tire at 46 PSI.

Do the chalk test and see what parts of your tire is actually touching the road.

 

Reference Discount Tire - Load Inflation Tables - E Rated Tires

BFGoodrich LT265/75R16 has a load Index of 123 for an E Rated Tire.

Lets say a fully loaded FJ Cruiser might get to say 7500 lbs Gross Weight, which is 1875 lbs per tire.

As per their tire inflation chart - E Rated, Load Index 123.

35 psi - 1910 lbs x 4 = 7640 lbs Gross Weight
40 psi - 2100 lbs x 4 = 8400 lbs Gross Weight
45 psi - 2280 lbs x 4 = 9120 lbs Gross Weight
50 psi - 2470 lbs x 4 = 9880 lbs Gross Weight

35 psi should be about right for this tire, unless you are really loading it up, then bump them up to about 40 psi.

Chalk test shows that at 46 PSI (door sticker), only the center part of the tire is touching the road, so you will experience center wearing over time. Even at 40 PSI, chalk test still shows only 75% center contact - still too high. There is something wrong with this minimum 46 psi number, which comes from the NHTSA, not Toyota. Toyota is just passing it on as they are required to by law.

 

I was at 42, and decided to try 37 out yesterday. Actually rode much better so I think i'll keep it around that for a while.

 

I should have some chalk test photos soon for 35, 36, 37 and 38 for the BFGoodrich LT265/75R16 E Rated Tire (Stock Tire on the TT).

My guess is 35-37 psi should be very close for the stock weight of the FJ Cruiser with only 2 adults, add more if you are carrying extra weight or towing a trailer. I believe the new TPMS setting is 34.5 psi, so I would not suggest going lower than 35 psi.

46 might be the recommended tire pressure if you have it fully loaded, roof rack full, 5 adult passengers and are pulling a big trailer. Perhaps the government has picked 46 psi for worst case situations (maximum weight) only to cover their butts is the vehicle is fully loaded and pulling a 5000 lb. trailer. For everyday driving with 1 or 2 adults, 46 psi is overkill.

I'd like to see some other chalk test results posted for LT265/75R16 BFGoodrich or similar E Rated Tires.

 

If you can slide a business card an 1/8" between the tire and the pavement you should be very close to your ideal tire pressure for your ride.

 

38 psi Chalk test comes out nice and even. Ride is very smooth with no steering vibrations.

40 psi is a bit too high with 3/8" of the edges not touching the road. Ride is smooth with no steering vibrations.

46 psi is way too high, with 1.5" of the edges not touching the road. Ride is hard and stiff with excessive steering vibrations, especially on curves.

Tire Inflation Charts for LT tires run as low as 35 psi, so this is not out of range for a lighter vehicle like the FJ Cruiser.

Some other similar weight trucks from Nissan and Hummer run in the 37-41 psi range for these LT tires.

 

Good to know, thanks for the info. I've run BFG ATs (275/70-17) pumped at 38 psi for 10,000 miles. Wear looks pretty even, will try the card trick/chalk test.

No way I'm going to 46 psi.