Tire Pressure Chalk Test - BFGoodrich KO2 - 265 70 16 - 2014 TRD OR DC - My Results

I just got a new set of BF Goodrich K02 tires and Discount Tire set them at 36 psi (front) and 38 psi (rear). I took her down to the beach and aired down for the soft sand sections. After airing back up to 35 psi (front) and 37 psi (rear), I completed the chalk test.

I made a nice thick chalk mark and drove straight 5-10 mph for about 150 yards. I have about 250 lbs of Snugtop camper shell weight on the bed. Here's some photos of my results.

For now I'm going to pick 34psi as my optimal front pressure and keep the rears at 32-34psi.

Rotate often!

 

What load range are these? Based on your chalk test I'd consider dropping the fronts to 34 and the rears to 32 and then retest.

 

Load range E

Can you explain why? Really interested. Thanks.

 

There is still chalk showing on the edges, especially on the rear. That indicates over inflation. The center of the tires will wear out sooner since the edges aren't in contact with the ground.

 

This.

 

ok, but doesn't it make sense to run the rear a bit harder for occasional hauling weight in the bed?
I also thought that a small amount of chalk on the very edge was desirable?

 

When you are actually hauling a load, up the pressure. I run the rears on my F250 at about 36 when it's empty and up to 70 when I'm actually carrying a load. Longer tire life and smoother ride.

 

I have a dusty alley and I was able to check perfectly every day, and my magic number was 27 winter 29psi summer front and rear no load (265/75r16 e). Plus it makes the ride much softer.

Don't be afraid to go lower on the front, but as you said, in anticipation of load keep the rear slightly higher.

 

I agree. The rears only need more pressure than the fronts when you are hauling a full capacity load in the bed.

 

Im going to edit my post and try 34psi front and 35psi rear. I load the bed frequently but rarely more than 200 lbs.

I will try to retest this week.

 

If 200lbs is the max you load, then I would still say 32 in the rear. 200 lbs is just one average sized dude. If the loading characteristics of the truck and the tires were that finicky that it needed adjustment as you took on and let out passengers then there'd be a lot more crashes.

 

TW needs more of this type of thread.
Informative and illustrative.

 

Is this where I tell you your truck sucks and your mother dresses you funny?

I couldn't agree more, this is something that gets folks thinking and maybe making a difference with.

 

Interesting. On my 2013 Baja (Aluminess bumper and Demello sliders) with the older version 265/70 16 E TaKos the door jam sticker said 46 psi and gave a very harsh ride with the Bilstein 6112/5160 set-up that came on the Bajas. I put the newer version TaKos on my new 2017 TRD OR and Discount set them at 37 psi. I haven't done the chalk test yet, but bet the 37 psi will be close, certainly better than 46 psi! I'll get back here after I install the Bilstein 6112/5160 set-up on the 2017, and chalk them, also after I install the RCI sliders.

Good thread folks

 

Sorry for the delay in updating my thread. The Houston weather has not been chalk test friendly. Just did another test today. I'm working my way down to @Maticuno suggestion.

The tires were really hot today and I drove the same distance as last time.

Does anyone know why Toyota specs the OEM rear tires at 32 psi (3psi higher than the front spec at 29psi)?

 

On the assumption that you might actually be hauling something in the bed. The ability of your tires to carry their rated load depends entirely on the air pressure inside of them. That's why E rated tires have a much higher max pressure rating. The door sticker on my F250 calls for something like 70 psi for the rears, but that's only if I'm loaded for bare. I run 36 front and 34 rear if I'm unloaded.

As for the recent chalk test, your fronts look almost there, and just a bit more out of the rears.

 

Somewhat on topic, I ordered KO2s on wheels from Tirerack this week. They came in mounted and balanced, but guess what the pressure was? Drum roll

85-90 PSI o on all four. That's not a typo. 85 PSI!!! Why in the world would they do that?

I did a chalk test today at 35 and still had a little left on the outside. Will test out 32ish tomorrow.

 

I’ve running 34 front and 32 rears or really close to that for pavement and it’s been perfect. Carry a pump on board to air them up for hauling/towing or after going off road.

 

Just did my chalk test. I have the same BF Goodrich K02 tires on my 2015 double cab. I got 33 up front and 32 in the back with no load. I live in AZ, it isn't that hot yet so I'll have to do this again when it heats up. I think I'll have to go down a few PSI to compensate for the expansion.

 

I remember those..weren't they a distributor add-on?

There are two reasons why they spec'd a seemingly high PSI.

-An LT265/70/16 has the lowest volume compared to other LT tires in the same diameter(16").

-Toyota neglected to account for de-rating when using an LT in lieu of a P or euro metric tire...

It should have been a recommended 40 PSI.