Cooper ST's - 255/85/16
- Thread starter ShearPin
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Redline
Likes to Drive and Ride
Cut/Chip Resistance Compounds
You raise an interesting point I was thinking of posting in the general mods section, that of Cut & Chip resistant treads being harder (or not) than regular tread compounds.
For years I assumed that cut/chip resistant tires were harder, and by being a harder compound they were less likely to tear (cut/chip). But I have asked a couple of the managers at the Les Schwab store where I do most of my business (a couple different times) if cut/chip resistant tires were made from a harder or softer compound. They said a softer compound, and will often wear faster.
I assume they know what they are talking about. Maybe it depends on the tire & manufacturer. A softer compound might not tear as easily as one with less give that will rip apart on sharp rocks, but I'm also aware that many treads that are marketed as cut/chip resistant are rugged, long lasting tires. If their rubber was so soft how do they last so long and survive commercial use?
Cooper's Site
On Cooper's U.S. flash website they have a sliding scale in the lower left corner to indicate a rating for noise, wet/dry traction, treadwear, handling, off-road, and winter traction. When you change it from the ST to the ST/C the scale indicates better for off-road use but a bit less for winter traction. The indicators reverse for the regular ST, meaning the ST is better for winter traction but not quite as good for off-road.
In my mind a softer tread would be better for winter traction - snow/ice (the regular ST).
Am I all wet?
You raise an interesting point I was thinking of posting in the general mods section, that of Cut & Chip resistant treads being harder (or not) than regular tread compounds.
For years I assumed that cut/chip resistant tires were harder, and by being a harder compound they were less likely to tear (cut/chip). But I have asked a couple of the managers at the Les Schwab store where I do most of my business (a couple different times) if cut/chip resistant tires were made from a harder or softer compound. They said a softer compound, and will often wear faster.
I assume they know what they are talking about. Maybe it depends on the tire & manufacturer. A softer compound might not tear as easily as one with less give that will rip apart on sharp rocks, but I'm also aware that many treads that are marketed as cut/chip resistant are rugged, long lasting tires. If their rubber was so soft how do they last so long and survive commercial use?
Cooper's Site
On Cooper's U.S. flash website they have a sliding scale in the lower left corner to indicate a rating for noise, wet/dry traction, treadwear, handling, off-road, and winter traction. When you change it from the ST to the ST/C the scale indicates better for off-road use but a bit less for winter traction. The indicators reverse for the regular ST, meaning the ST is better for winter traction but not quite as good for off-road.
In my mind a softer tread would be better for winter traction - snow/ice (the regular ST).
Am I all wet?
..............Snip............... It almost seemed like the S/T-C's entered a different mode of traction. Instead of trying to have soft rubber gripping the ice, I think I had so much pressure on the hard rubber tread of the 245's that the tread blocks were mechanically biting in. It was all pretty surprising.........snip........
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R_Lefebvre
Expedition Leader
I NEVER assume tire dealers (or almost anybody else for that matter) have any idea what they're talking about. I always look for a second, third, fourth opinion... Yeah, some people hate me, but it's served me well. You'd think the "professionals" would know exactly what they're talking about, but they often don't. Anyway...
I noticed the same thing you did about the winter traction, and at first I was bummed when I ended up with the S/T-C's by accident since I use them in the winter. But, after driving in the winter with them, they left me wanting for nothing. They're like any "All-season" on hard cold ice, they're awesome in the snow, and pretty good on warm soft ice. I never had any problem on cold dry pavement either, though I do drive this truck prudently anyway. If I had this rubber on a car, maybe I'd notice more of a difference.
There are a few more things going on than just "hard and soft" rubber. Good modern winter tires have a "silica" rubber compound. It's not that they're absolutely softer, but rather than they do not stiffen up as much as regular rubber compound when the temperature drops. I'm not sure what the disadvantage to silica is, and why they don't put it in all tires. My guess is just cost, which is borne out by the fact that cheap winter tires don't have silica rubber, which is why they suck even though they are winter tires.
Similarly, there are certain rubber compounds that just hold up better to high temperature and high stress. Lots of guys go to trackdays with expensive high performance street tires because they say they "can't afford" racing tires, or don't want to bother with a change over. They go out, and chunk and completely destroy a $1200 set of rubber in one day. I use R-compound tires because I believe "different horses for different courses" and it's served me well. I get many many track days out of my tires if I'm careful. The rubber is soft, but I don't think that's really it.
I use Toyo RA-1's, which are a hard R-compound. Many other people use super soft ultra high performance street tires which are probably just as soft as my R-compound, but don't last nearly as long under the stress of track use. Even though the durometer is similar, the street tires chunk anyway.
I noticed the same thing you did about the winter traction, and at first I was bummed when I ended up with the S/T-C's by accident since I use them in the winter. But, after driving in the winter with them, they left me wanting for nothing. They're like any "All-season" on hard cold ice, they're awesome in the snow, and pretty good on warm soft ice. I never had any problem on cold dry pavement either, though I do drive this truck prudently anyway. If I had this rubber on a car, maybe I'd notice more of a difference.
There are a few more things going on than just "hard and soft" rubber. Good modern winter tires have a "silica" rubber compound. It's not that they're absolutely softer, but rather than they do not stiffen up as much as regular rubber compound when the temperature drops. I'm not sure what the disadvantage to silica is, and why they don't put it in all tires. My guess is just cost, which is borne out by the fact that cheap winter tires don't have silica rubber, which is why they suck even though they are winter tires.
Similarly, there are certain rubber compounds that just hold up better to high temperature and high stress. Lots of guys go to trackdays with expensive high performance street tires because they say they "can't afford" racing tires, or don't want to bother with a change over. They go out, and chunk and completely destroy a $1200 set of rubber in one day. I use R-compound tires because I believe "different horses for different courses" and it's served me well. I get many many track days out of my tires if I'm careful. The rubber is soft, but I don't think that's really it.
I use Toyo RA-1's, which are a hard R-compound. Many other people use super soft ultra high performance street tires which are probably just as soft as my R-compound, but don't last nearly as long under the stress of track use. Even though the durometer is similar, the street tires chunk anyway.
Redline
Likes to Drive and Ride
I agree about the the professionals not necessarily knowing their stuff - multiple sources are good and I'm more inclined to believe Cooper’s website that the ST/C is not quite as good for winter traction as the regular ST. I thought of calling Cooper to see if I could get an answer form customer service, maybe next week.
I do know and agree that tire compounds and designs are complicated and not simply hard or soft, and I believe there is lots of stuff in modern tires other than rubber. I’m sure your racing experience has taught you much about tires.
I do agree that having the right tool for the job, in this case tires, is important. Better to have two or more sets of tires and wear them less than half as fast by using each for their most appropriate purpose.
(Edit: A tire engineer subsequently old me the Cooper site was wrong. The softer, chip-resistant S/T-C compound is better for winter driving.)
I do know and agree that tire compounds and designs are complicated and not simply hard or soft, and I believe there is lots of stuff in modern tires other than rubber. I’m sure your racing experience has taught you much about tires.
I do agree that having the right tool for the job, in this case tires, is important. Better to have two or more sets of tires and wear them less than half as fast by using each for their most appropriate purpose.
(Edit: A tire engineer subsequently old me the Cooper site was wrong. The softer, chip-resistant S/T-C compound is better for winter driving.)
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24HOURSOFNEVADA
Expedition Leader
Nope your spot on as usual. A softer tread will give you better traction in the snow/ice.
I used to have a great video on winter tires from Tire rack and it went into some detail on this very topic (Tire compounds for winter driving).
R_Lefebvre
Expedition Leader
It's not that simple. Question, what is better on ice, soft sticky ultra high performance tires, or winter tires? Obviously the winter tires. And not necessarily because of the tread. The performance tires are softer in warm weather, but harden in cold weather. The Silica in the winter tires keeps that rubber softer in freezing temperatures. I believe there is a cross-over point at about 7C.
cjmitchell5
Adventurer
Does anyone have a definitive word on availability on the 255/85 Discoverer S/T? I need three of them. I've called a few places and it seems noone has them in stock or can locate any. Has anyone contacted Cooper? I have three tires now; what do I do w/ three tires? :sombrero:
Redline
Likes to Drive and Ride
I spoke with Cooper customer service twice this past week, and I'm waiting to be contacted by an engineer regarding the tread compound differences between S/T-C and S/T.
I asked specifically about what tires they currently offer in 255/85R16, the Cooper S/T was the answer. The woman I spoke to made no mention of the tires not being available or in production.
This doesn't mean that stock isn't low and availability could be poor. Another example of this is the new BFG KM2. The 255/85 KM2 is currently on backorder and not available but will be again after more are made.
Nylon Tread Plies
The first time I spoke to this woman at Cooper earlier in the week she told me that in 2007 a nylon tread ply was added to ALL 16-inch tires. At that time I informed her that I have a set of 255/85 S/Ts and that they only had 2-steel and 2-poly tread plies. When I spoke with her a couple days later she confirmed that she had learned that the implementation of the 16-inch nylon tread plies had not been fully implemented and she was waiting for confirmation as to construction of the tires.
Deck Cepek, Mickey Thompson, Pro Comp
Obviously these companies don't manufacture their own tires and somebody else makes them for them. I have always heard that it was Cooper, which makes perfect sense, as Cooper makes lots of private label tires (many Dean tires for Les Schwab, plus other brands). Cooper customer service confirmed that yes, they do make these tires.
I asked specifically about what tires they currently offer in 255/85R16, the Cooper S/T was the answer. The woman I spoke to made no mention of the tires not being available or in production.
This doesn't mean that stock isn't low and availability could be poor. Another example of this is the new BFG KM2. The 255/85 KM2 is currently on backorder and not available but will be again after more are made.
Nylon Tread Plies
The first time I spoke to this woman at Cooper earlier in the week she told me that in 2007 a nylon tread ply was added to ALL 16-inch tires. At that time I informed her that I have a set of 255/85 S/Ts and that they only had 2-steel and 2-poly tread plies. When I spoke with her a couple days later she confirmed that she had learned that the implementation of the 16-inch nylon tread plies had not been fully implemented and she was waiting for confirmation as to construction of the tires.
Deck Cepek, Mickey Thompson, Pro Comp
Obviously these companies don't manufacture their own tires and somebody else makes them for them. I have always heard that it was Cooper, which makes perfect sense, as Cooper makes lots of private label tires (many Dean tires for Les Schwab, plus other brands). Cooper customer service confirmed that yes, they do make these tires.
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cjmitchell5
Adventurer
Well, good news, I just received a message that my tires will be in by next Wednesday. I need to paint my wheels and get them mounted, photos will be forthcoming
cjmitchell5
Adventurer
2 spares, I'm still looking for a good way to bed mount them. I'd like a bed toolbox but the kind that sits in the bed like a chest and put the tires on either side. []chest[]
that's a picture
that's a picture
jim65wagon
Well-known member
Well, I did it. Got my new ST's on Friday (yes in 255/85). Local shop. 187.50 per tire mounted and balanced. Not too bad considering the best online I could find was for 160 + shipping + M&B. (4 x 160 = 640 + 80 S&H + 40 M&B = 760) (187.50 local x 4 = 750).
New ones have, of course, 18/32 tread....old ones ended life at about 5.5/32s. Just a hair over 50,000 miles. That's 4000 miles per 1/32".
At that rate I could have legally gotten 8,000 more miles out of them; and my stingy cheap side says I should have. My slightly sensible side says in 8000 miles I'd be in the middle of fishing/camping/beach season and would be hard pressed to find the time for a new tire install.
This is the first time I've ever replaced tires with the same tread and/or size. The old ones were amazingly loud and rough compared to how smooth and quiet the new ones are. I'm set for two more years of fun!
New ones have, of course, 18/32 tread....old ones ended life at about 5.5/32s. Just a hair over 50,000 miles. That's 4000 miles per 1/32".
At that rate I could have legally gotten 8,000 more miles out of them; and my stingy cheap side says I should have. My slightly sensible side says in 8000 miles I'd be in the middle of fishing/camping/beach season and would be hard pressed to find the time for a new tire install.
This is the first time I've ever replaced tires with the same tread and/or size. The old ones were amazingly loud and rough compared to how smooth and quiet the new ones are. I'm set for two more years of fun!
Redline
Likes to Drive and Ride
That's great news Jim!
Glad to see you purchased a second set. That is some excellent wear you obtained out of those S/Ts. I got similar service out of my first set of "Wild Country" TXRs in 255/85 on my '96 F350 several years ago, a tread with a similar void-ratio.
It's interesting how much louder tires get as they wear. I wonder if the tread depth is part of the equation? Are the new tires made with the same construction, two ply poly sidewalls and a 4-ply tread (2 steel 2 poly)?
It would be nice if you could say you got 58K out of the old set but at what cost? We all know shallow tread depth doesn't do much for traction or safety on or off-highway. If you need to console yourself after buying new tires watch this TireRack video ☺.
http://www.tirerack.com/videos/index.jsp?video=5
Glad to see you purchased a second set. That is some excellent wear you obtained out of those S/Ts. I got similar service out of my first set of "Wild Country" TXRs in 255/85 on my '96 F350 several years ago, a tread with a similar void-ratio.
It's interesting how much louder tires get as they wear. I wonder if the tread depth is part of the equation? Are the new tires made with the same construction, two ply poly sidewalls and a 4-ply tread (2 steel 2 poly)?
It would be nice if you could say you got 58K out of the old set but at what cost? We all know shallow tread depth doesn't do much for traction or safety on or off-highway. If you need to console yourself after buying new tires watch this TireRack video ☺.
http://www.tirerack.com/videos/index.jsp?video=5
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jim65wagon
Well-known member
Yes, they are the same 4ply tread and 2ply sidewall construction. I think it's all a tread depth issue....maybe the deeper channels absorb some of the sound waves?
Thanks for the vid, I've seen it before and I know what running very shallow tread will do for you....I'm just a cheap, stingy old man at heart and not using something to it's fullest will always bug me.
If it makes you feel better I ditched the original tires off the truck at 15,000 miles because they were unsafe in anything but dry weather. The Coops at 6/32 felt safer in a rain than the Rugged Trails at 10/32. Yeah, I've always had a depth gauge in the garage.
Not to worry, safety of family outweighs a stingy wallet every time!
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Redline
Likes to Drive and Ride
I really don't care for the stock Rugged Trail tires that come on some new Toyotas. I have a few friends with new ('05-up) double cab Tacomas, completely stock and still with the original tires. The Rugged Trails look not rugged to me, shallow tread depth and all, even when new.
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