Correct tire air pressure??
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4RnR Grl
New member
On road, 35-40 PSI. On trail, around 20.
Florunner78
New member
35 psi for the road, 275/70 KO2. Best compromise between fuel economy and ride quality I've found. 32 rides noticeably better, but there's a MPG hit.
toku58
New member
Every tire is different! You can get a ball park PSI by asking. But the true way to get the correct PSI is the let your tire tell you what it needs!
Load range, brand, side wall stiffness, weight of your vehicle etc..... will all play a factor.
So I would recommend that you fill your tire and take notice how the threads are contacting the ground. You want to fill it enough so that the entire thread makes contact. Too much air and the center of your tire will wear, too little pressure and the out side will start to cup.
Depending on the tire you have the pressure can vary greatly.
Load range, brand, side wall stiffness, weight of your vehicle etc..... will all play a factor.
So I would recommend that you fill your tire and take notice how the threads are contacting the ground. You want to fill it enough so that the entire thread makes contact. Too much air and the center of your tire will wear, too little pressure and the out side will start to cup.
Depending on the tire you have the pressure can vary greatly.
old.ink
New member
Chalk Test
Hi,
This is a need to know and please take in consideration. All depends on the tire brand, the load range, what is in your vehicle, winter or summer, on and off road and more...
The PSI will be different from 285/70 All-Terrain Falken in the winter with no added weight vs 285/70 MT Toyo in the summer with bumpers and RTT, for example.
The best way to find your PSI is doing the chalk test, look on youtube or google it.
For me, in my case I ran 34 PSI in the winter and 32 PSI in the summer, with my 285/70s Falken AT3W. The chalk test proved to me that 34 and 32 psi is what I need in those two weather condition with my T4R set up. That is gonna change soon because Ill be adding racks, tent, suspension to my rig.
So please, do the chalk test and find your best psi.
Good luck
Hi,
This is a need to know and please take in consideration. All depends on the tire brand, the load range, what is in your vehicle, winter or summer, on and off road and more...
The PSI will be different from 285/70 All-Terrain Falken in the winter with no added weight vs 285/70 MT Toyo in the summer with bumpers and RTT, for example.
The best way to find your PSI is doing the chalk test, look on youtube or google it.
For me, in my case I ran 34 PSI in the winter and 32 PSI in the summer, with my 285/70s Falken AT3W. The chalk test proved to me that 34 and 32 psi is what I need in those two weather condition with my T4R set up. That is gonna change soon because Ill be adding racks, tent, suspension to my rig.
So please, do the chalk test and find your best psi.
Good luck
Throwback
New member
Check out the sticky at the top of the section this thread is in:
http://www.toyota-4runner.org/engin...s/110299-lt-tires-need-more-air-pressure.html
I used the Tire & Rim Association's Load & Inflation Tables for the following:
https://toyotires-1524598101.netdna...ication_of_load_inflation_tables_20170203.pdf
Your stock "P-metric" tires in 265/70/17 at 32psi (door sticker) have a max load of 2425lbs.
To achieve the same max load capacity in an "LT" tire in 285/70/17 you need 45psi which gives a max load of 2510lbs.
The lowest listed psi of the LT tire is 35psi which gives a max load of 2100lbs.
32psi should get you about 1950lbs of max load. Around 1900lbs below OEM spec tire cumulative load capacity.
http://www.toyota-4runner.org/engin...s/110299-lt-tires-need-more-air-pressure.html
I used the Tire & Rim Association's Load & Inflation Tables for the following:
https://toyotires-1524598101.netdna...ication_of_load_inflation_tables_20170203.pdf
Your stock "P-metric" tires in 265/70/17 at 32psi (door sticker) have a max load of 2425lbs.
To achieve the same max load capacity in an "LT" tire in 285/70/17 you need 45psi which gives a max load of 2510lbs.
The lowest listed psi of the LT tire is 35psi which gives a max load of 2100lbs.
32psi should get you about 1950lbs of max load. Around 1900lbs below OEM spec tire cumulative load capacity.
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The "LT Tires need more pressure" link is a good read, but it is one dimensional thinking to assume that load capacity is the only factor that vehicle manufacturers use in determining tire pressure. In fact, they take into account
- load capacity
- fuel economy
- sidewall heating (related to load capacity and fuel economy)
- contact patch uniformity across the tread
- handling characteristics
- hydroplaning resistance
- and other stuff I haven't mentioned.
As a first rule, you need adequate load capacity. However, just because a p-rated tire at 32 psi has 2500lbs of capacity doesn't mean you need that much out of an LT tire. You'll never get much more than half that load on a single 4runner tire.
Back in the 70's it used to be common for the door sticker to recommend 24 psi for a p-rated tire for a 4000 lb Cadillac or Olds sedan. The low pressure made the ride nice and smooth. Why the change over the years to the now common 32-35 psi for roughly the same weight vehicle? Fuel economy, pure and simple. Secondarily, handling. People expect tighter handling characteristics these days than they did for a 1970 Caddy.
Best is to look at the load chart for your tire. At a minimum put in enough air to handle any expected load with a 25% reserve. Then adjust air pressure above that to balance comfort, fuel economy, and handling. Do a chalk test to check contact patch, and keep an eye on your tires for uneven wear across the tread.
FortCollinsT4R
New member
Nitrogen is a total hoax. There's 70% nitrogen in regular ol' air.
Throwback
New member
Is 25% enough over a static load? I don't know the engineering behind what calculates the full weight load of the front tires under full emergency braking with the nose diving down nearly to the asphalt. Surely it's more at that moment than whatever static load is accounted for.
I've had my 4Runner for less than a year and run 5 different sets of tires on it as trial and error. The factors you list are absolutely valid and you cannot get optimal levels of each when running a non-OEM spec tire.
I had 265/70/17 C KO2s and when running at 45psi for proper load rating I was losing a huge percentage of contact patch and the suspension spring rate was all screwed up. Not bad when cruising down the highway, but under duress or emergency maneuvering it was not something I'd let my wife drive.
On the flip side at 35psi I got a good contact patch but lost at least 4mpg from stock, had slow sloppy handling, and the obvious lower than spec weight capacity.
My annual highway mileage is around 18,000 so even if I run 180 miles off road annually the percentages (99% highway) are way in favor of safer and better highway handling over slightly better off road puncture resistance.
To each his own, of course, but this issue seems largely misunderstood and ignored.
Load rating primarily has to do with sidewall flex and resultant steady state heating at highway speeds. As such, the momentary excess load due to a panic stop isn't really an issue, any more than is running your tires at 18 psi offroad. Sidewall heating is negligible in both cases.
BTW, I would extend your statement "you cannot get optimal levels of each when running a non-OEM tire" to "you cannot get optimal levels of each when running any tire". Even the vehicle manufacturer's recommendation is a compromise of all of those factors. But, they do have the advantage of more engineering knowledge, plus a lot more test dollars and time, to optimize the combination of factors.
I run 40 psi in my 255/75/17 C-rated KO2's. So far handling feels good, tire wear (after 8000 miles) looks acceptable, and I haven't taken a noticeable hit on mileage. We'll see how the tire wear progresses.
BTW, I would extend your statement "you cannot get optimal levels of each when running a non-OEM tire" to "you cannot get optimal levels of each when running any tire". Even the vehicle manufacturer's recommendation is a compromise of all of those factors. But, they do have the advantage of more engineering knowledge, plus a lot more test dollars and time, to optimize the combination of factors.
I run 40 psi in my 255/75/17 C-rated KO2's. So far handling feels good, tire wear (after 8000 miles) looks acceptable, and I haven't taken a noticeable hit on mileage. We'll see how the tire wear progresses.
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Throwback
New member
This is why I decided to just run OEM spec tires since my 4Runner is my primary vehicle and spends 99% of it's time on the road. So far I've been very pleased with the P-rated Michelin LTX AT2 in all conditions, though I avoid heavy mud. It's an amazingly capable vehicle with the e-locker and KDSS even on mild AT tires.
I've thought about procuring a set of FJ steelies and getting a set of BFG MTs to swap on for weekend trips if I ever get into more aggressive off roading, but I would not want to run those daily.
