Cooper ST's - 255/85/16

[ashooter]

...After a trail run last weekend at full tire pressure on some sharp rocks there are a lot of chunks missing.

And that right there is the reason I was considering the Toyos in the first place.

SOAZ - You've had your S/T's for a couple of years, right? I heard that the Aussies had a LOT of problems with chipping like this. I wonder if the S/T-C is the result, or if the Aussies got a bad lot of S/T's, or some of both...?

It'd be nice if they made the S/T-C in a 255/85. (one could hope, anyway)

 

[Redline]

Post 113 Page 12 quote below talks about air pressure.

Remember it is the volume of air that supports the weight, not only the PSI. A 255/85R16D carries 3,000-lbs at 65-psi while a 235/85R16E carries that same weight (3,042-lbs) at 80-psi. I will likely NEVER run more than 35-psi on my 4Runner unless I need it for towing, and I often run a bit less. My F350 usually runs 35 in the rear when unladen and about 45-50 in the front. On-highway PSI is increased as needed for the load on the F350 or 4Runner but the 4Runner only sees a few hundred added to the rear axle while the F350 might see a few thousand.

Desert Dude:

I thought of something that is related to your rotation/balance question; tire pressures.

I don’t run lots of air-pressure, even on my F350. It has never seemed to cost me MPG or tire wear, and I believe it assist with traction. handling and ride quality. I don’t run low/under-inflated tires, merely appropriate PSI for the load. Light loads means less PSI, more weight requires more PSI. On my lighter vehicles (Jeep/Toyota) it is easy to pick one on-highway PSI that works on the car and stick with it unless you like to play with things like I do.

My practice.

An LT255/85R16D and LT265/75R16D both are rated to carry 3,000-lbs per tire in a SRW (single rear wheel) application at 65-PSI. Since few of us are driving 4x4s weighing 12,000-lbs (6k on each axle) this is too much pressure. The tires will be overly firm, hurting both ride quality and traction.

At 35-PSI the 255/85 is rated for 1920-lbs and the 265/75 is good for 1910-lbs. That is close enough to not matter and I will use the 255/85 capacity as that is the size I prefer. At 35-PSI there is still much more capacity than is usually needed, 3,840-lbs! I don’t think it is bad to simply run 35-psi, but I don’t think people need to go above that for better MPG. The tires are already pretty pumped-up unless the truck has 3,840-lbs on each axle.

The inflation charts I have seen don’t go below 35-psi and maybe that is because there are no standards for less psi, but I don’t accept the notion that the tires are not safe to be run at lower than 35-psi if the load is light for a given tire. An example of this is on my ‘06 4Runner. According to Toyota and the sticker on the door jam the stock P265/70R16 tires were rated to carry 3,295-lbs at 32-psi on the rear axle. The front axle is only rated for 2710-lbs and Toyota suggests the same 32-PSI (KISS I believe). These are the gross axle weight ratings (GAWR) for the vehicle. If the axles are carrying less weight, and they are even after all my modifications, they don’t really even need the full 32-psi. Remember this is after the Ford Explorer/Firestone mess and I’m confident there is extra capacity built into this 32-psi number for Toyota’s legal department. Why 32 instead of 35, because 35 is overkill and overall ride, handling, and traction will be better with and appropriate, lower psi.

This doesn't mean that I run 25-psi on the highway, but I have experimented with pressures below 30-psi. My current air pressure for my 4Runner is 32, just because that’s what Toyota recommends, it rides and drives well and the TPMS sensors don’t put a light on the dash. I have experimented with less, and just yesterday drove a short distance with 35, which I promptly bled out upon returning home as it didn’t feel right. I’m not finished experimenting ☺

 

[Redline]

Yep, for what your have described the Cooper ST sounds better than the possible 'overkill' of a Bighorn or BFG. I haven't run the BFGs on the 4Runner enough miles, but my Bighorns throw rocks. 24HRSOFNEVADA and I drove on lots of fast gravel roads (with Bighorns) en-route to the '07 ExPo Trophy and the front of my Chaser shows it. Of course we were driving in a spirited manner, so maybe any tire would have left its mark?

The Toyo M55s do have the advantage of being chip resistant. I read all the ‘chunking' info I could find, including the Aussies, but still decided to give the STs a try.

My 4Runner is heavy and I know its weight from measuring it at truck scales. Estimates are okay but can be very inaccurate. In addition to just knowing, weighing a rig to know the empty & laden weight is very helpful when trying to run the appropriate PSI for the load. I know the FJ80 is a heavy truck, but stock I don't think they weigh much more (probably less) than my modified 06 4Runner. Before leaving for the ExPo Trophy 24HRS and I weighed our trucks, both with and without the Chasers trailers. I can't remember 24HRS exact weights but I do remember that my gross combined weight for 4Runner & Chaser was something like 80-lbs more than his. His FZJ80 had a ARB front bumper & winch. My Gross was 7,840-lbs! 4Runner by itself was 5,800-lbs loaded, with no passengers or trailer on the hook. Add me and gross combined weight was over 8,000-lbs.

See my other post about tire PSI and weight.

Redline,

First, THANKS for all the info - both directed at me, as well as just general tire info you have posted at this site.

I do think from a purely practical standpoint, the Coopers are probably the best thing out there for my use. The Toyo M-55 might be better, but at $100 more per tire they'd have to be a whole lot better! The BFG KM/KM2 or the Maxxis Bighorn would undoubtedly be overkill because of the fact that there just isn't any mud around here (West Texas). Even when it rains 3 inches in an hour, the deepest mud I've ever seen is about 4-6 inches on top of solid rock.

One of the things I like about the Cooper is that I've read in a couple of reviews how the driver was pleasantly surprised at how they don't pick up and throw rocks. Even these Revos toss more than a few, and I can imagine a full blown mud terrain would sound like popcorn.

Vehicle weight: Your 4-Runner is HEAVY! I think stock weight of my FJ80 is about 6000 lbs, so we're close. With my idea of a full load, plus future ARB front bar, I'm guessing weight on the ground would still be under 7000 lbs. 80's are pretty heavy, but not heavy like a loaded down diesel pickup is heavy. Load range D "LT" tires ought to be plenty.

I'm surprised you only run 30 lbs in your 4-Runner! I run 40 lbs in load range E 265 Revos and it rides good... even though part of me wants to air them up to 45. I've heard a couple of guys running 255 BFG KM's on FJ40 and FJ/FZJ80 Cruisers talk about running them at 60 lbs+! Is there a formula for figuring out how much pressure is "correct"?... And if so, does the formula fit ALL tires or is it dependent on tire size/construction?


?

 

[ashooter]

Interesting info regarding vehicle weight, tire pressure, etc.

I must have been thinking 3295-lbs plus 2710-lbs equals 6005-lbs equals the weight of my truck. Obviously, based on the actual weight of 24HOURSOFNEVADA's FZJ80, my FJ80 is probably substantially less than that. I've stripped a bunch of cr@p off of and out of this truck since I got it and have zero plans for sliders, skid-plates, cargo boxes, fridges, etc so you're probably right about me being able to get away with a lot less air in the tires than I'm accustomed to.

Thanks again for all the info!

 

[maybe_a_80...]

Gettin' them STs for sure

So guys, I just read this entire post last night...wow there is alot of info and expertise here. Thanks.

I just bought a 96 FZJ80 that will be my DD here in Utah. I got it cause it's a luxury truck that is ridiculously capable for whatever situation I might get myself into. So, it's gonna see mostly pavement at first. I still want it to look ************ (Redline calls it a Mall Crawler). I would have purchased a new GMC Sierra with Autotrac but 32k is just out of the question.

I ran 235/80R17s (Wrangler Slient Armor 10-ply) on my company rig, a 08 GMC Sierra SLE1 Ext Cab 8' bed. I put narrow tires on strictly because they do well for driving in snow at highway speeds, which is all the company rig ever did. By the way the Silent Armors are awesome snow tires. They have the mountain/snowflake symbol on them. And you can get 50k out of a set.

An interesting note to narrow tires - rally cars are equipped with narrow tires for snow events. I am firm believer in trickle down - if it works well in the most demanding competition situations, it should have SOME- TO ALOT- of relevance for more normal applications.

Due to this experience, I believe in narrower tires for highway snow driving. I will get a set of 255/85R16s put on my TLC before the snow flies this fall for 4 reasons.

1. They are a great traction tire from what I can gather and will give me a narrower tire for deep snow road driving.
2. Like the rest of you, I think tall narrow tires look ************!
3. The cost of Cooper Discoverer STs is low compared with other similar tires.
4. Of the 255/85 tires, the ST seems the least oriented to strict MT criteria.


I'll keep everyone posted - this will very much be a road-based vehicle so the application is a little different and the experience should be good to add to the significant expedition-based application for which most of you are using the tires.

 

[Redline]

Good job jumping right in with some tire comments

Welcome to the ExPo.

You are correct about the Cooper STs, they are certainly the least aggressive of the commonly mentioned & used 255/85R16 tires on this forum.

 

[Hilux_Max]

in regards to fitting 255's on your truck, would it be better to fit them on a stock rim, i.e. closer tucked inwards due to clearance issues or would it be better to get a wider offset rim and do some trimming to fit and gain the benefit of a slightly wider track?

I think going the wider track would help considering you'd be lifting your vehicle abit anyway, you'd need the stability aswell.

 

[maybe_a_80...]

in regards to fitting 255's on your truck, would it be better to fit them on a stock rim, i.e. closer tucked inwards due to clearance issues or would it be better to get a wider offset rim and do some trimming to fit and gain the benefit of a slightly wider track?

I think going the wider track would help considering you'd be lifting your vehicle abit anyway, you'd need the stability aswell.

Thanks...I am planning on running the stock rims at the moment...my FZJ80 will get a 2" OME lift kit when money permits so that should solve the problem. I don't expect to really 'wheel my rig anytime soon either. My general plans with my fzj80 are to keep it super clean looking with minimal exterior changes beyond more aggressive "expedition tires" (also for nasty weather performance) and the 2" lift.

I'm pretty sure there should be no clearance issues for general driving with the stock set up and 33" inch tire, from what I have read here and on ih8mud.

Any enlightenment would be much appreciated. Remember - my fzj80 will not see any serious trail time in the foreseeable future.

 

[maybe_a_80...]

Good job jumping right in with some tire comments

Welcome to the ExPo.

You are correct about the Cooper STs, they are certainly the least aggressive of the commonly mentioned & used 255/85R16 tires on this forum.

Cool spot you've all got here.

I figure the Cooper Discoverer STs will do a damn good job of keeping me rubber side down when coupled with the AWD on the FZJ80 in nasty Western winter weather on I80, I84, I70, US40, etc.

I would get the Wrangler Silent Armors in a second if they made a 255/85 as I believe the tread pattern to be far superior to any of the M/T tires or the Discoverer ST for driving on icy roads. But I want 33" tires on my FZJ80.

 

[Streakerfreak]

After having these Cooper Discovery 255/85R16s laying around the shop for a few months and trying to get them sold I decided to just put them on.

They fit great!

 

[sami]

A little help here from some guru's please?

This thread has been a great read and source for info!

So after lifting my '99 4runner with the 2-3" OME kit, i'm looking around for tires to compliment the addition in altitude.

I've found an incomplete set of (3) never mounted 255/85R16 load range D all terrain Kelly Safari AWR tires, for about $250 intalled. I've made countless phone calls to locate a 4th matching tire, to no avail.

It's up to me to find a 4th tire to complete the set.. To which i've found a Cooper Discoverer Radial LT 255-85-16, never used off of a '99 Superduty for about $60.

So we're talkin a full set of 4 tires installed for roughly $300. I figure I could pick up another Discovery Radial LT to run, and use the odd Kelly as a spare. So say two Kelly AWR's up front, and two Discoverer LT's in the rear, with a Kelly AWR spare.

Thoughts? Comments?

Kelly Safari AWR

Discoverer Radial LT's

 

[Redline]

Were you planning on getting a correct size, 255/85 spare?

It will cost you a bit more, but you might consider buying the three Kelly AWRs, then find two more 255/85 in a different but similar tread. The third AWR is your spare and run the other tires with different but matched tread front and rear.

 

[sami]

Were you planning on getting a correct size, 255/85 spare?

It will cost you a bit more, but you might consider buying the three Kelly AWRs, then find two more 255/85 in a different but similar tread. The third AWR is your spare and run the other tires with different but matched tread front and rear.

Yep, last line of my previous post

So you think it might be an ok deal/setup?

 

[Redline]

Sorry, I didn't read your post that carefully.

If your truck is not full-time 4WD I think it would be fine. You just have to be satisfied with the different treads.

Remember than many (most) large/commercial 2WD trucks run different treads on the steer and drive axles.

Yep, last line of my previous post

So you think it might be an ok deal/setup?

 

[Hilux_Max]

just wondering, has anybody got a set of the Toyo's fitted to their vehicle yet and if so maybe a test report?

some pics wouldnt go astray either of them fitted to a vehicle.