Cooper ST MAXX thread

We only have white boards. I think I have some here at home

 

These look great!

I didn't know Cooper makes this tire in the stock OR size. I was just looking on their website along with America Tires website and can't find the LT265/70/16 listed anywhere. Is this tire size such a new offering that it is not on their site?

 

They had to order it. They were 204 each. 265/75 are like 180 each, but I didn't want to change the gear ratio for upcoming towing.

 

Wow that is great to know they can special order the stock OR size...because I am in the same boat I don't want to size up and mess up the stock gear ratios....speedo...and mpg anymore than a heavier tire will anyway.

Do you happen to know what the weight per tire is on that ST-Maxx LT265/70/16?

 

It's actually been suggested that these numbers are more accurate in the 265 75 16. Just a thought.

 

Thanks for the feedback. I have had heard this too....but when I ran a separate GPS on my Tacoma the speedo with the stock tires and wheels was basically right on.

 

54 pounds.

 

Just a fyi...
39 psi is the converted tire placard pressure for that tire size and load.
You mentioned you'll be towing, so...

1 psi=36lbs of load capacity on your tire.
Say you chalk it at 35psi...

39-35=4psi
4psi x 4 tires=16psi
16psi x 36 lbs=592lbs load capacity

 

Where did you get that info? That's awesome

 

If you extrapolate the oem tire loads and psi for Offroads, Sports, and SRs they all want a load capacity of 2,149 lbs with P or ISO metric tires.

P/245/75/16/109 @ 32 PSI=2,172
265/70/16/112 @ 30 PSI=2,149
P/265/65/17/110 @ 29 PSI=2,149

P/ISO metric is derated for use on trucks by a factor of 1.1; LTs need not be derated. So LTs require 2,149/1.1=1,954.

A LT/265/70/16 is rated for 1,820 lbs at 35 psi and 2,000 lbs at 40 psi.

So...
2,000 lb-1,820 lb=40 psi-35 psi
180 lb=5 psi
36 lb=1 psi

and

2,000lb @ 40 psi-1 psi=1,964lb @ 39 psi.

Here's a link to load charts
https://toyo-arhxo0vh6d1oh9i0c.stac...ication_of_load_inflation_tables_20170203.pdf

 

Z50 is a HS math teacher, you just gave him some homework material...
I'm sure his students are beyond basic math though..

 

That honestly confused me. Do variables such as long bed and double cab come into play on that as well? Also aren't the wranglers on the OR P-rated? Getting mine installed tomorrow 255/80/17

 

No, those variables are not a factor.

Wranglers are ISO metric; notice, no "P" prefix. ISO metric uses a different load chart than P metric.
I edited to show each one, in my confusing post.

Where'd I lose you?

 

The difference from iso to Lt. Is the load for the size assumed or should it be pulled from manufacturer website

 

Relevant, but not 3rd gen.

 

ISO is different than P.
ISO doesn't care about size; just load index.
P cares about load index and size.

Download the pdf I linked earlier and go to page 30; this is the ISO chart.
Load index 112 @ 30 psi gives a load capacity of 2,149 lbs.

Go to page 11; this will explain de-rating by a factor of 1.1. 2,149 dived by 1.1=1,954
This de-rating rule came about because of the Ford-Firestone fiasco. It applies to both P and ISO.

Go to page 23 to find what psi is required in a LT/265/70/16(single) to attain 1,954 load capacity.

 

I think I know why I'm so confused. I'm looking at a different size than you are in the LT and it's got me all messed up in the numbers department.

 

This chart is for optimal payload right? Optimal wear would be lower psi?

Edit: assuming we are not towing anything

 

Correct; you could think of it as your max tire pressure.

I'll admit, I'm coming from a different mindset.
I can regularly and without notice haul 500+ lbs.
My wear is excellent too.