Picked up a set of Cooper Discover AT/3's for the Jeep Liberty KK

[cobra_4]

Finally got my much needed tires! I've had great luck with Coopers over the years so I didn't see any reason and changing up a good thing! These are a little noisy and ride a little rough, but I think that's just the old age setting in! Can't wait to try them off road!

Went with one size bigger, 245/70/16's. These should last me a while, then it will be lift time before the next set!

 

[jhill15]

Nice man! I recently picked up a set of these as well. So far i'm really happy with them

 

[1stDeuce]

A little noisy?? You mean they make enough noise to be heard, not that they make unacceptable levels I hope!

I can't hear them at all on wifey's KJ, but it is a CRD, and has enough wind leaks that a cat could get out without using the doors...

As for the ride, you might want to check tire pressure... With the size being one up from factory, and the design being more of an LT than P, you should be at or slightly below the recommendation on your door sticker. Many tire shops inflate them to whatever the tire says on the side, which is WAY too high...

We can get away with about 3psi lower than the sticker before the TPS light comes on in our Liberty... But if it's a cold morning, it'll sometimes be on for the first few miles of driving. The actual pressures are displayed on the overhead, so we just do a quick check and head out.

Chris

 

[cobra_4]

A little noisy?? You mean they make enough noise to be heard, not that they make unacceptable levels I hope!

I can't hear them at all on wifey's KJ, but it is a CRD, and has enough wind leaks that a cat could get out without using the doors...

As for the ride, you might want to check tire pressure... With the size being one up from factory, and the design being more of an LT than P, you should be at or slightly below the recommendation on your door sticker. Many tire shops inflate them to whatever the tire says on the side, which is WAY too high...

We can get away with about 3psi lower than the sticker before the TPS light comes on in our Liberty... But if it's a cold morning, it'll sometimes be on for the first few miles of driving. The actual pressures are displayed on the overhead, so we just do a quick check and head out.

Chris

Yeah, after driving it again, I kinda take back the noise complaint. They aren't bad. I think they were noisy when I was "listening" for it.

I gotta check the pressures, I have no idea what they are, but your probably right, a little high.

 

[outback97]

Just took our first trip with new A/T3's this past weekend, and both my wife and I noticed how quiet they were. Couldn't really hear them at all over other wind and engine noise in the Xterra. Ours were 38-40 PSI.

 

[1stDeuce]

Just took our first trip with new A/T3's this past weekend, and both my wife and I noticed how quiet they were. Couldn't really hear them at all over other wind and engine noise in the Xterra. Ours were 38-40 PSI.

You mean the tire shop delivered them at 38-40, or that you're running them that high? I should think closer to 30psi would be best for an Xterra.

I don't mean to be the tire pressure nazi, but too much pressure = worse tire wear and reduced performance on most surfaces, and in some cases can lead to downright scary handling!

 

[outback97]

You mean the tire shop delivered them at 38-40, or that you're running them that high? I should think closer to 30psi would be best for an Xterra.

I don't mean to be the tire pressure nazi, but too much pressure = worse tire wear and reduced performance on most surfaces, and in some cases can lead to downright scary handling!

Not a problem at all, always open to learning something new. I have them at 38 cold, the 40 was what I read after they warmed up, should have been more specific.

I just got these last week, this was our first day trip with them, and I prefer running tires a little higher than the door placard. I think it recommends 35 but I'd have to check it and see. I would not run 30 on the highway, but for gravel roads that would be smoother.

I really do need to do the chalk test and play around with PSI a bit. This was the first trip we've had on the tires, so still figuring out the best setup. Handling was great, they were a bit stiff but I attribute that to the E load range as much as the PSI.

 

[1stDeuce]

Again, unless you overload your vehicle, or are running smaller than stock tires, the placard on the door is really the highest pressure you would normally want to run. A stiffer or larger tire will take slightly less pressure than your OE tires to get even wear and good ride quality and traction. The chalk test can be very telling, and my guess is that it'll tell you that you're on the high side. And 30 on the highway is nothing to fear for a large tire on a lighter vehicle, particularly if that's what it takes to get good even contract pressure across the tread. (Like on my 4000lb Jeep with 255/85's.) It's all relative.

 

[texascrane]

Again, unless you overload your vehicle, or are running smaller than stock tires, the placard on the door is really the highest pressure you would normally want to run. A stiffer or larger tire will take slightly less pressure than your OE tires to get even wear and good ride quality and traction. The chalk test can be very telling, and my guess is that it'll tell you that you're on the high side. And 30 on the highway is nothing to fear for a large tire on a lighter vehicle, particularly if that's what it takes to get good even contract pressure across the tread. (Like on my 4000lb Jeep with 255/85's.) It's all relative.

I'm certainly not an expert, but I don't think that's how it works at all. In fact, if you go to a larger and/or stiffer tire, I believe that you generally need to increase your tire pressures to maintain the same load carrying capability as the stock tire. This guide from Toyo walks you through the process of determining appropriate PSI on pages 88-90:

http://toyotires.com/sites/default/files/page-files/LoadInflation_Table_P-LT_102913.pdf

 

[CSG]

Exactly right, texascrane! I've been researching this issue for my own LX which is running C load 265/75/16's. For years, I ran them about what the door sticker said for P275/70/16's. I should have been running them higher all along. There is so much bad advice given on forums and tire shops that it's downright scary.

To the OP, cobra, did you buy the P, C, or E versions of this tire? I talked to a gal named Pam at Cooper a couple days ago and she suggested I get the P versions even though I explained I off road on a lot of rock strewn trails. I don't know who she was regarding qualifications but even though they make that tire in a P version, I cannot wrap my head around using less than a C for off roading.

 

[Allof75]

Not to turn this into a tire pressure thread, but I believe TexasCrane is right, low tire pressures on high profile tires are what led to the whole Explorer rollover debacle, among poor construction and other things. Certainly overinflation (60 psi in the liberty for instance) can lead to scary handling, but keeping it at 38 won't, and will in fact give you better mileage, and sometimes better wear. Underinflation is what's dangerous, especially when taking corners at higher speeds, such as on a highway, where the deflection of the soft sidewall can cause squirm and result in a loss in control in certain situations. Test out what psi works for you, but typically between 35-40 is completely safe. 30 is probably fine too, but much less and you're running into risks. Heavier duty vehicles like large 3/4+ ton trucks routinely run 60psi.

Anyway, congrats on your Coopers, I like mine a lot, and hope they last you a long time.

 

[1stDeuce]

Run what makes you happy, but if you run chalk tests, you'll find that as the tire gets bigger, it takes LESS pressure to "properly" inflate it and carry the same load. But within reason, running higher pressure than necessary is definitely better for your health than running too low a pressure.

Ford set the factory recommended tire pressure on Explorers to 26psi on an effort to get the ride to be more "car like". It was a stupid move, and if you chalk tested those tires, you'd have run about 33 in them, because we did it on my roommate's '98 explorer, and that's what he ran. Fairly low pressure in a pretty heavy vehicle with somewhat small tires is a recipe for disaster in the heat, and Ford delivered it and then passed off the blame to Firestone because they didn't object to the low pressure. Total BS IMO, but that's not what we're talking about here.

If the OP feels safe with with his pressures, then he should run them at those pressures, if only for his peace of mind. But I really believe that a chalk test would show he's just a little high. With the exception of the Explorer, getting even tread contact on a stock or larger than stock tire has NEVER required more pressure than the door sticker, in my experience of doing the chalk test.

I do agree that tire shops often give scary information, but the only way larger tires need MORE air pressure is if you want to carry more weight on them. Pressure needs to be proportional to the surface area that's carrying weight... As the surface area goes up, the pressure required to support the same weight goes down. So if you want rock hard tires in terms of ride quality, run higher pressures, but if you want the tire to function as a part of the suspension like it should, then you have to drop the tire pressure slightly to get the same amount of sidewall flex that a smaller tire would have.

That's the mechanics behind it. If you want to suggest or believe otherwise, that's fine, but do fall back on chalk test when you can, as that's really the final word. If it says you need higher pressure, then run it.

Chris

 

[texascrane]

Run what makes you happy, but if you run chalk tests, you'll find that as the tire gets bigger, it takes LESS pressure to "properly" inflate it and carry the same load. But within reason, running higher pressure than necessary is definitely better for your health than running too low a pressure.

Ford set the factory recommended tire pressure on Explorers to 26psi on an effort to get the ride to be more "car like". It was a stupid move, and if you chalk tested those tires, you'd have run about 33 in them, because we did it on my roommate's '98 explorer, and that's what he ran. Fairly low pressure in a pretty heavy vehicle with somewhat small tires is a recipe for disaster in the heat, and Ford delivered it and then passed off the blame to Firestone because they didn't object to the low pressure. Total BS IMO, but that's not what we're talking about here.

If the OP feels safe with with his pressures, then he should run them at those pressures, if only for his peace of mind. But I really believe that a chalk test would show he's just a little high. With the exception of the Explorer, getting even tread contact on a stock or larger than stock tire has NEVER required more pressure than the door sticker, in my experience of doing the chalk test.

I do agree that tire shops often give scary information, but the only way larger tires need MORE air pressure is if you want to carry more weight on them. Pressure needs to be proportional to the surface area that's carrying weight... As the surface area goes up, the pressure required to support the same weight goes down. So if you want rock hard tires in terms of ride quality, run higher pressures, but if you want the tire to function as a part of the suspension like it should, then you have to drop the tire pressure slightly to get the same amount of sidewall flex that a smaller tire would have.

That's the mechanics behind it. If you want to suggest or believe otherwise, that's fine, but do fall back on chalk test when you can, as that's really the final word. If it says you need higher pressure, then run it.

Chris

If you look at the inflation tables, what you'll see is that your statement is true if you're moving within the same type of tire. However, in this case, he has moved from a p-metric to an LT tire. There's more going on than just the changes in air volume, surface area, and PSI.

Assuming, the OP had p-metric 235/70r16 tires at 32psi that puts him at a load capacity of about 1720 lbs. Moving to an AT3 245/70r16, which is an LT E-rated tire, he would need to be at 38psi to achieve that same load capacity. If instead he had moved to another p-metric 245/70r16, then his pressures would indeed need to decrease in order to achieve the same load rating.

 

[outback97]

Just to clarify, I don't think the OP even stated what PSI his were:

Yeah, after driving it again, I kinda take back the noise complaint. They aren't bad. I think they were noisy when I was "listening" for it.

I gotta check the pressures, I have no idea what they are, but your probably right, a little high.

I did mention that ours were at 38:

Just took our first trip with new A/T3's this past weekend, and both my wife and I noticed how quiet they were. Couldn't really hear them at all over other wind and engine noise in the Xterra. Ours were 38-40 PSI.

I still need to do the chalk test on mine and see what I come up with. So far still really liking the A/T3's.