255/85 R16 Owners Experience

Again?

Where did you try to buy from? Could be they were just out of stock for the moment.

 

I purchased mine from a local shop. Based on your question you need to inquire with a local retailer or contact Cooper directly.

Good luck. I would buy the ST Maxx again.

Salt

 

Cant find em locally or online. TireCrawler says they are on natl backorder.

 

hi all,

just mounted 255/85/16 with about a 2 inch lift right now.

they're great, much to say but trying to figure out highway psi.

does this look right? seems very low:

KM2's: 3415 @ 80psi x 4 = 13660 total capacity

2008 TRD Double Cab Short Bed: 4220 curb weight = ~30% of total tire load capacity

so 80psi x .30 = 24.7psi

running at 34 right now just to get home. was gonna try chalk test...but always a crap shoot.

any insight much appreciated

 

These are some pressures that people have posted to give you an idea. I believe im running 35psi all around, but thats not neccesarily right, but i havnt had time to do the chalk test.

24.7 does seem low though

 

PSI vs load is not linear. Check for load charts based in the type of tire you use now. I think I posted links to charts earlier in this thread.

 

Thanks all.

generally pretty good on forums but after about 50 clicks and 10 searches still coming up short. really sorry to bother and bee a noob, but if anyone has a link to the load chart for the KM2's would be much appreciated. just read through the thread in wheels in "what my psi...", and only take away seemed to be the chalk test

maxx found load charts for the toyo, pretty complicated PdF, was that what you were referencing.

and totally makes sense that it's not linear

 

tread depot had them back in stock today - but when i called they only had 6.. i spoke to cooper manufacturing last week and was told they were being made at that time and that workers were working over the thanksgiving wknd doing a big run in this size. i ordered some today for my jk!

 

The chalk test is the only accurate feedback that you can use. The issue of temperature also comes into play. My pressure goes up with the temp as the compound is definitely softer in the summertime. With Cooper Discoverer S/T I run about 48 when it is single digits and close to 60 when it gets around 90 in the summer. I run about 20 when I hit the trails.

 

The chalk test is not an accurate measure of proper inflation. Just because a tire sits "flat" on the road doesn't mean it is inflated properly.

The load carrying capacity of the tire is strictly based on the pressure inside the tire. And we know what those capacities are based on tire pressure. This should be a good starting point to make minor adjustments from.

Here is a detailed post I created talking about tire pressure, tire construction and load capacity: http://www.tacomaworld.com/forum/wh...onship-between-psi-load-lt265-lt255-data.html

There is a link to the Toyo website with load tables in my post. Towards the end of the PDF are TRA specifications for all tires. These are not specific to Toyo tires, but to ALL tires made to the specification. An LT255/85R16 Load Range E tire from Toyo, Cooper or BFGoodrich will have the same load carrying capacities.

 

Only 2 left. You got the last set of 4 lol.

 

Wasn't me that got them, somebody else got lucky I guess! I ended up ordering mine from a shop a few hrs away in my previous city, ended up being$375 less than tread depot for 5 including install.

Hope you find some soon if you're still looking! They should be hitting the shelves all over very soon.

 

Ok so I'm going to get a icon 3" C/O lift for my 2015 DCSB tacoma and was wondering if the 255/85/16 km2's would fit on stock off road rims would I need to trim or should I be ok?
Thanks, Andrew

 

You'll be fine. maybe minor plastic trimming at MOST

 

No trimming needed for me with the billy and AAL lift

 

Thanks guys and is that including going offroad on trails and what not?

 

I respectfully disagree on several points, but find your post about tire inflation and load to be quite impressive.

The chalk test is not only accurate feedback, displaying the amount of contact with the road surface, but it can be done quite easily in a variety of environmental conditions.

When done with a bit of common sense, it is a great guideline. I would suggest starting at a high pressure and driving under acceleration, braking, and both left and right hand turns at low to moderate speed to determine when you have full patch contact. Continue lowering the pressure until this is achieved.

From my work at a rubber compounding/forming company, which included custom tire fabrication, you should be well above the load requirement when you achieve full contact. Drop another 5 percent from that value and you should have even wear and a safety factor for loading so that a pothole doesn't cause rim damage.

Additionally, I was wondering what you used to determine the load requirements? Did you use min or max loading? What kind of lateral acceleration values, and what kind of a modifier for a lifted truck versus stock? Are you assuming that all four wheels are loaded, or did you use three in the case of off-roading or blowout? When off-roading I have teetered from one group of three, onto two while tipping then onto three as the center of gravity shifted, but the speed was less than one mph.

Did you see my comment about temperature? Generally, manufacturer's make charts for ambient temps of 70F or 75F, and rely on a safety factor for a usable range of -20F to 120F. The compounds are weaker as the temperature climbs, and a surface temperature above 240 typically causes the lubricants to boil off.

I think if you run a D-rated or E-rated tire below 40psi at speeds above 50mph you will see a lot of premature wear, some pretty poor mileage, as well as fatigue cracking on the sidewall.

 

Funny, because I think we are both at the same conclusion, based on your last comment. If I do a chalk test, with my rear axle weight of 2100lbs (static split of 1050 lbs per tire on the street), the amount of pressure that results in an "even" chalk wear is likely well below the table-calculated pressure. And many here are below 40 even with lots of freeway driving.

And everything is a compromise, so the ideal pressure when traveling a freeway at 70 MPH is quite different than what is needed in an extreme off-road situation. Many Euro cars say to increase pressure to max for any extending driving over 100.

In the end though, I doubt any manufacturer uses a chalk test to develop their pressure specs. Even acknowledging that they aren't looking for longest tread life but "safest" operation.

Best advice should be a combination of methods. Use the chalk test, but make sure the minimum pressure is still within guidelines. LT tires start at minimum 35 psi, and even running LR-E tires on a Tacoma, 40psi would be a good starting point.

 

Do you have wheel spacers or not? That's look I really am aiming for!

 

Any pics?