Chalk Test on BFG AT KO C rated 265/70/17

[WindomEarles]

I finally did a chalk test on my BFG AT KO C rated 265/70/17 tires.

https://docs.google.com/file/d/0BxvlBpVATdHpNHJkMFpISDYzMVk/edit?usp=sharing <-- Rear tire

https://docs.google.com/file/d/0BxvlBpVATdHpakUyamRGYVQ3NmM/edit?usp=sharing <-- Front tire

I'm running 45psi in them. The front looks really good (only about a 1/4 inch that didn't get worn off). The rear is a little different story (there's about 1 inch that didn't get worn off).

Seems like I should be fine as long as I rotate regularly at this PSI? I could always drop the back down a little bit, but I dunno. Thoughts?

 

[WindomEarles]

The funny thing is, I swear I saw about an inch when I was running 38psi too in the rear. I could see where the salt was leaving marks in the middle but it was clean around the edges.

 

[03_4x4Runner]

I would say 45 is to high. I have been running 37-38 psi on my 03 with the exact same tires for 40k miles and they wore very evenly. It must ride like a tank with 45 psi. Do a search on this also. It has been discussed in the past with this same tire.

 

[WindomEarles]

For a c rated tire, you need to put in more air. It's about 45 psi to support same weight as stock p rated tires.

 

[1engineer]

For a c rated tire, you need to put in more air. It's about 45 psi to support same weight as stock p rated tires.

See, that's where everyone screws up. You are not hauling the weight around. You are only hauling about 1200 lbs a tire around. How much does the chart say for that? If your tread is not touching especially 1" of it they are over inflated.

 

[WindomEarles]

See, that's where everyone screws up. You are not hauling the weight around. You are only hauling about 1200 lbs a tire around. How much does the chart say for that? If your tread is not touching especially 1" of it they are over inflated.

Thanks for the info! I'm gonna do chalk until it is only about 1/4 inch see where it lands.

 

[Gerdo]

For a c rated tire, you need to put in more air. It's about 45 psi to support same weight as stock p rated tires.

This is incorrect. The differences in C, D & E rated tires comes in the max capacity. They carry the same weight at the same pressure. The higher load rated tires will ride rougher due to the extra belts in the tread area but that doesn't carry the weight (at lower pressures), it just allows for a higher max pressure (which allows for more weight capacity).

 

[Gerdo]

For a c rated tire, you need to put in more air. It's about 45 psi to support same weight as stock p rated tires.

I just noticed that you were comparing pressures of P and LT tires.
True, A LT tire will require more pressure than a P tire to carry the same weight. But only a few PSI.

 

[scanny]

It's been discussed before, as per Toyota manual and common sense the load capacity of new tires doesn't have to match load limits of the stock tires. Tires (LT or P) should be able to handle weight of the truck + maximum load. Toyota refers to maximum wiight per axle wicj in on door sticker too. Then you should check load tables for LT tires and see what tire pressure is required. I don't remember exact numbers and I'm not sure that my post will be seen at all with todays web site troubles, but the bottom line is that stock size LT 17" tires will support T4R weight + maximum allowed load at about 35 psi. Probably it's a good idea to run 36-38 psi so you won't get lower that minimum pressure but in general pressure over 36 psi is an overkill.