Dummies' Guide to Setting Correct Inflation on Your 5th Gen 4Runner Tires

[the_economist]

There are a lot of threads out there about tire inflation. However, I haven't seen a step-by-step "dummies guide" for new owners that walks through how to do the PSI math yourself using tire load tables.

So here goes!

These are the steps for setting the correct (on road) tire inflation on your 5th Gen 4Runner after getting rid of your OEM tires and upgrading to LT tires (in this case, BFG KO2s).

Note: This is an approximate guideline based on Toyota engineer's own views about the tradeoffs between MPG, ride quality, and what you're actually doing with your truck. If you like to run your tires low or high, fine -- this guide isn't for you.

Step 1. Find the OEM tire size and pressure for your 4Runner:
2016 Toyota 4Runner Recommended Tire Pressure Settings - TirePressure.com
-We all know this, it's P265/70-17, 32 PSI.

Step 2. Look up the maximum load capacity those OEM tires at the Toyota recommended 32 PSI tire pressure:
P265/70R17 Tire Pressure Chart - TirePressure.com

-The maximum load of the OEM tires is 2,425 lbs at 32 PSI.

Step 3. De-rate the OEM P-rated maximum tire load from Step 2 by a factor of 1.1 (Why? Because they can carry less weight on a truck than on a passenger car. See here for more details: https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=70):
-2,425 lbs / 1.1 = 2,205 lbs.

Step 4. Go to the tire pressure chart for your new tires (in my case, 275/70-17s). Look for the maximum load you calculated in Step 3 (2,205 lbs) in the "single tire" row -- single means 2 tires per axle, double means 4 tires per axle, and you're probably not running dualies on the rear axle of your 4Runner! See what PSI pressure that corresponds to in the table:
LT275/70R17 Tire Pressure Chart - TirePressure.com

-In the table, 2,205 lbs is very close to the maximum load in the table for 40 PSI, which is 2195 lbs. So 40 PSI it is!

Need even more help? Here are step by step instructions for a bunch of different examples:
How To Apply Tire Load Inflation Tables When Replacing Tires - TirePressure.com

Need another resource on how to read load tables from the US Tire and Rim Association (the group that produces these tables)? See here: https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf

Have fun!

 

[Old Tanker]

I recently swapped from the stock Duellers to Falken Wildpeaks. Your tire pressure chart would have me dropping the pressure down to 29psi. Before I do that, I think I'll spend an hour this weekend playing with chalk stripes along a quiet road, and see what pressure results in even chalk wear across the width of the tire.

 

[jhguth]

I'm very confused by those inflation tables, they dont show load ratings. Not every tire of a certain size will have the same load rating at a given pressure, it depends on the load rating.

Am I just not seeing it in the chart?

 

[the_economist]

I'm very confused by those inflation tables, they dont show load ratings. Not every tire of a certain size will have the same load rating at a given pressure, it depends on the load rating.

Am I just not seeing it in the chart?

The load range on LT tires (C, D, E, etc.) determines the maximum possible inflation you can push into a tire before it blows. The more weight you want to carry, the higher the PSI you'll need in your tire, regardless of tire size.

For example, the max pressure on any C-rated LT tire is 50 PSI, the max for an E-rated LT tire is 80 PSI, and so on (source: Understanding Tire Load Ratings).

However, the guide above is not about the maximum PSI any tire can accept, but how to set the optimal tire pressure, given the weight of your 5th Gen and the tire size and P vs. LT construction you'll be running. Plenty of links above to read more about this.

 

[jhguth]

The load range on LT tires (C, D, E, etc.) determines the maximum possible inflation you can push into a tire before it blows. The more weight you want to carry, the higher the PSI you'll need in your tire, regardless of tire size.

For example, the max pressure on any C-rated LT tire is 50 PSI, the max for an E-rated LT tire is 80 PSI, and so on (source: Understanding Tire Load Ratings).

However, the guide above is not about the maximum PSI any tire can accept, but how to set the optimal tire pressure, given the weight of your 5th Gen and the tire size and P vs. LT construction you'll be running. Plenty of links above to read more about this.

You still need to know the load index which those charts dont show, not every tire of a load range has the same load index. The load index is the numbers after the size

 

[5thToy]

It's not that black and white (except when running @ max GVW). If it were, Toyota wouldn't ship different trims of the same vehicle with vastly different load ratings. Limited gets 107, the rest get 113. What are you going to use for a baseline? For everyday driving, there is a working range depending on tire construction, vehicle weight and personal preferences for ride, wear and fuel economy. To simplify my point about working range, The 4Runner comes with 107 and 113 load ratings and all door stickers call for 32 psi.

 

[ElectroBoy]

This calculation determines psi for max load. Are you driving around with the max load your 4R can handle?

 

[SnowYeti]

I recently swapped from the stock Duellers to Falken Wildpeaks. Your tire pressure chart would have me dropping the pressure down to 29psi. Before I do that, I think I'll spend an hour this weekend playing with chalk stripes along a quiet road, and see what pressure results in even chalk wear across the width of the tire.

I really don’t pay any attention to the cold psi. Given the extreme temp changes here in Colorado gauging my tires cold when it is 30 degrees in the morning makes no sense when it could reach 80 degrees. I gauge psi at running temps after the tires have come up to temp. I over-inflate the tires then do a chalk test to find the best psi for ride and tire wear by just letting air out until I just barely get full tread contact edge to edge. Then I adjust as needed as the seasons change. My perfect psi is 38 running temp in my AT3Ws in 275/70/17. Tire wear has been very even and I can tell without looking if they are low or high based on the ride quality. I have done this for decades with great results. With a bigger AT tire setting and forgetting year around in a state like CO is a big mistake.

 

[4gambler]

My 2 worthless cents.

In a 4wd runner i do 2 psi more in front than rear.

 

[NCArcher]

65PSI it is!

 

[Dreaded_Marauder]

So I’ve been going over this for a while running 255/75/17 KM3’s and the only thing that I have not been able to find on any load inflation table is the correct oem tire. We have 113xl they inflate to 51 psi max not 35 that’s a huge difference. I figured calculating with the 1.1 we should be about 1800 lbs and not 2200 lbs for stock weight at 32 psi. That puts me at about 34 psi with the tires I have. Been running them at that with Ko2’s in the same size before that and the middle wore a smidge faster so I know I’m in the ballpark. If someone finds more appropriate load inflation for our oem Bridegstones let me know. Good stuff though, I kinda obsess over this.

 

[MossJenks]

Or you could not overthink it to death and just set them to a nice even number like 35 psi. (Or 34 or 36 or whatever you feel like. Most tire gauges aren't accurate enough to really know the difference)

 

[MossJenks]

65PSI it is!

:banana:

 

[Dreaded_Marauder]

Just got off the phone with Dunlop/Goodyear and the load our tires hold at 32 psi is 1590lbs. That’s before you derate them with the 1.1 calculation. I’d say we need to be around at least 1600lbs on a load inflation table. So with my 255/75/17 KM3’s at 35psi I’m rated at 1890 so 32-35psi is perfectly fine for tire pressure. There’s no need to run our tires with LT’s any higher than that.

 

[1jzgte]

dude.. an LT tire at 32 with 75 sidewalls? Try the chalk test .. yes its tedious but 32 is severely low psi for a that particular tire..acceleration must feel terrible at that pressure.. Your km3 at that size max's out at 50 cold psi... so you got lots of room to experiment..

dunlop/goodyear etc etc wont argue against OEM tire pressure recommendation and risk a lawsuit at their doorstep.

 

[Dreaded_Marauder]

Im purely basing all this off the correct load to psi and my tires at 35 psi will carry the load required. They feel great anywhere from 32-40 psi. When I ran my Ko2’s at 35 for about 28k miles the middle wore about a 32nd more than the edges. So 35 is totally in the ball park for even wear for my 4runner with the load I carry. I could run them at 40, but I’d wear the middle out faster for sure.

 

[CROWN14]

Trial & Error

I’ve been running LT285/70’s Toyo A/T 2’s for six years. E rated for max 80 psi.
I did much of the same research early on. I knew from the start that the 32-35 psi the tire dealer recommended was way too low for a 10 ply tire. I started at 45 psi, drove on them for a few weeks and started adjusting them down from there.
My goal was to maintain even tread wear and control the harsh ride of too much air and body roll of too little air. I found in the summer months they are best at 38-40psi. In the colder months I lower them to 35psi and adjust my rear shocks to a stiffer setting to account for the body roll. It’s really a personal choice.

Good Luck

 

[JLofa]

Lol I thought this thread was going to be about inflation prices and selling
Good stuff though