Gross Weight and Tires

I am still looking at the Cooper ST 265x75x16 STD load tire (not the LT 265)

My gross weight when we went camping was 6820 lb. 2900 lb on the steer axle and 3920 on the rear axle. That makes the max for each tire would be around 2000 lb.

Looking at Cooper's web http://coopertires.com/us/en/ProductDetails.asp?ProdType=SUV&id=190 http://coopertires.com/us/en/ProductDetails.asp?ProdType=LtTruck&id=190 the LT tire had less max load in the Load Range "C" than the STD (standard range) of the non LT tire.
Cooper makes the Discovery ST in a LT and standard rating (non LT) its not a P rated tire (I think)

The LT has max load of 2470 in the "C" rating
3000 in the "D"
3415 in the "E"

The nonLT tire max load is 2756 in the STD rating.

The price difference between the LT and nonLT it about $50 per tire.
$101 for the 265 and $156 for the LT265. I don't know which Load Range (C,D or E) the tire guy was quoting me though.

Why would I pay more $$$ for the LT when the nonLT gives me the load range I need?
Why would the LT cost more than the non LT?
Could the side wall be thinner in the nonLT?

Landtoy,
Thanks for posting this question. I'd noticed the same thing on the Cooper website, and really wonder what's up. Can't wait to read some responses!

My father has a Tundra and tows a 5th wheel trailer with it. His complaint was when towing the truck knid of wallowed in turns and didn't feel that stable. I had him put on some D rated LT tires and it took care of the problem. My tyhinking was that the better side wall construction would help with his problem, it seemed to, but now Mom complains that it rides like a truck.

IMO any vehicle the size of an 80 needs a D load range tire. The difference is quite amazing.

I can back up landtank on the Tundra. I use my father's 01 to tow a double axle car trailer, usually with some type of Land Cruiser on it. From wallowing to smooth and controled, changing over to a D range tire made all the difference.

The non LT tires are P rated that are sold in USA and Europe. Europe doesn't put "P" on there tires.
They also are a 4ply type of tire. The max psi is 32. The LT have a higher psi.
The tire man couldn't explain how the tires are rated as they don't rate the P tires the same as the LT tires.

I was going to go with the P tire to see if my MPG's would increase. I average 13mpg with LT285x75x16 WildCountryRVT mud tires.
If the increase in MPG was up to 17 mpg or better, I would get them.
I would be mad if I went and spent the $$$ on wimpy tires and the MPG didn't increase.

There's a lot going on with tires, and I'll try to simplify it as relates to the P/LT comparison on load ratings. The load ratings are directly comparable obviously, as they're both expressed in pounds. So, you can assume that a P tire rated for 2200lbs is equivalent in load capacity to an LT tire rated at 2200lbs.

However, they're designed for different uses. The P tire has a more flexible carcass emphasising ride qualities and MPG. It may have softer durometer rubber that will stick better but wear faster. The LT tire carcass is more rugged and durable. It may have harder rubber that will wear slower.

The LT carcass can better resist abuse such as being at or near its max and encountering rocky secondary road conditions or a very bad pothole that might separate the plies of a P rated tire, or even cause a P to fail. In some ways, the P rated tire is rated to carry its load on a typical road where the LT is rated to carry its load even on a rough mining road. That sentance is perhaps the entire key to comparing the types in terms of load carrying.

They may state the same number of plies on the sidewall, but the LT carcass may have thicker cords, thinner cords of a superior material, more expensive adhesives in the belts, etc that account for the added durability. These same differences also generally result in an LT tire's stiffer carcass that can better handle not simply the load like a P tire, but also do a better job of handling carcass deformation in corners that we feel as sway and wallowing. They do this by giving away desirable ride characteristics, of course.

One of the ways the extra durability is provided is simply more rubber to protect the carcass from damaging deformation and penetration. You'll see this difference easily in the "tread depth" column where the P tires have 15/32nds and the LTs have up to 20/32nds - a huge difference of up to 30% more rubber for wear and protection. Check out the S/T-C version and you'll see they mention a "chip resistant" rubber formulation that is a perfect illustrator for how seemingly identical tires intended for different uses are actually quite varied. I'd be willing to bet that C version would wear like iron for instance, but the hard compound would likely be a poor performer in terms of grip - not a good trade off vs the already stout heavy versions of the LT. But to a fleet owner wanting to get 50,000 miles out of his mining truck support vehicle tires it may be just the ticket.

So, you can get the load carrying ability in a P tire, but if you're actually planning to CARRY those loads a lot the LT has some safety considerations. To confuse the issue further, a P tire will likely provide better traction on an every day basis due to its stickier rubber and a softer contact patch that conforms more readily to the surface.

HTH,

DougM

My plan is/was to use the nonLT "P" Cooper Dis ST for daily Walmart use.
Get a second set of rims for my mullet tires when I go off road ( yea right, like I will ever have free time to have fun any more!!!)

Is anyone doing this?
Does the extra cost of two sets of tires and wheel pay for its self over time with the $2.07+ gas?

landtoy80 said:

My plan is/was to use the nonLT "P" Cooper Dis ST for daily Walmart use.
Get a second set of rims for my mullet tires when I go off road ( yea right, like I will ever have free time to have fun any more!!!)

Is anyone doing this?
Does the extra cost of two sets of tires and wheel pay for its self over time with the $2.07+ gas?

Click to expand...

well, let's see:
say you improve your mileage by 1mpg with road tires. You do 12,000 miles /yr. You go from 14 mpg to 15 mpg on the road. You save 57 gals/yr. At $2/gal, that's about $120 / yr saved.

Cost of 5 good big tires: $750
cost of 5 steelies: $350
Total wheels and tires: $1100

Payback time: $1,100/$120= 9 years.

Adjust as needed

(but you gotta change the wheels every time you go in the woods.
OTOH, you'll keep the wheelin' tires much longer and have fun with them...)
E

...and in 9 years you'll have worn out at least two sets of the road tires, so really the answer is no you'll not save the money back for decades.

Don't get me wrong. Correct tires for the application is the best way to go. Just don't try to justify the financial aspects of it, ya know? I run winter wheels and steelies as best way to go but never even thought about the financial 'payback' on safety. Not enough money in the world to replace my family.


DougM

Yea, I don't buy the math either but the other way around. If you ignore the cost of the capital then you are really only out the cost of the steel rims. When you've got the off-road tires on, then you are saving the on-road tires for another day (and vice versa).

But I think the best advantage is like Doug says... safety and better ride with the DDs on the truck.

Doug,

You use the Arctic Alpins over the Cooper ST, how are they in deep wet snow, slush and ice?
The tread on the Arctic Alpins look very tight and closed. I like a open lug tire for wet, snow and slushy roads.
Are the tires with closed side ribs make that way that way to keep the noise down or is there another reason other then longer tread life?
THe only reason, that I can see, for a closed tight tread pattern would be on ice and hardpack snow. I have run my mud lug tire on ice and hardpack snow with no problems.

Not sure which Alpin tread you're looking at, but I have the SUV version on the 80. It's the most open of all the Alpins. I also have the original Alpin for the Subaru, which is a very closed tread and as you surmised sucks in deep wet snow/slush. These are incredible on glare ice, however.

The SUV version on the 80 is a much better design. They do very well on all surfaces - retaining the incredible ice performance. I switched to them for ultimate traction on what I consider the highest probability scenario you need help on. That's basically coming up to a stop sign or light and discovering there's a long patch of glare ice as you begin braking - too late to do anything but decide what to hit. This area is known for a lot of black ice. The other scenario I consider a high probability concern is black ice in a curve.

The S/T I ran with studs and siped and it was not the equal of the Alpin on glare ice or its cousin polished hardpacked snow. However it did better on deep snow by far - something you as a driver can more often control simply because in this day and age we decide if we're going to head out on that unplowed secondary road. Since the glare ice thing is a daily and unexpected thing I felt the tire should focus on this as the greatest danger and it's worked exactly as I'd hoped for 2 winters now.

The other improvement the Alpin brought along was superior dry handling, but not by much - certainly not as much as you'd expect given the S/T's open tread. I find the S/T to be an excellent handler.

If you've never driven a dedicated winter tire on snow and ice, you're in for quite a pleasant surprise.

Having said all that, if I had to choose a single tire for winter and summer I'd choose the S/T. It's that good.

DougM

Doug,

Curious, what size Alpin are you using?

Thx

Doug, Called Copper and asked them about the ST. He said it is very popular with the farmers. He made it sound like its not a good hwy tire???
He said the new STT would work best for my vehicle for year round use.

I did ask him about the NEW STT. I saw it in a 4X4 mag. I think it will contend with the BFG MT. It will be out in late Nov.


Is this your Alpinhttp ://www.michelinman.com/images/catalog/tires/4x4_alpin_large.jpg ?
Does your mpg change when you run them over the ST?

I'm pretty sure my Alpin 4X4s are 265/75s. They're on a high shelf in the garage and I'll be dusting them off for winter in a few weeks. I've not noticed an MPG change vs the summer Michelin LTX's, but comparing winter vs summer MPG would not be accurate (cold starts and operating, etc).

As for the ST not being a good highway tire, I strongly disagree. The current STT would be a laughable highway tire, and I'm sure the new one will be better but I think someone at Cooper's smoking crack to feel the STT (a far more offroad series) would be better than the ST on the highway. Yes, that photo is the Alpin tire I run in winter on the 80. The Sube gets the one with near zero tread blocks.

DougM

Kurt, I have the LT version of those Coopers, siped. They're great on my long highway drives including loaded up with the family. Slightly noisier than my wife's new Michelin Cross Terrains. I bought them when I was hauling a trailer through construction sites, they're tough tires for running over debris and pulling through muck. I went with the LT for that toughness and more tread depth. A Cooper engineer told me they're all 2-ply these days, just 4-ply or 6-ply rated to indicate relative strenght. I looked at them because Doug had had good service from them, and I'd say they do wear and run well.

Scott, I am almost ready to try the ST. I have a rain check from Farm and Fleet for the LT285 for $119 each.
I like my Wild Countrys but with your advice I am leaning to the ST.

That's a smokin deal for the S/T's. Get 'em siped as well.

DougM

But for about $15 more I can have the Wild Country RVT
I love indecision

A guy at work is running the same size Coopers on his Avalanche, not siped, very happy with them year-'round. I bet they outlast the Wild Countrys.