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Old 06-28-2020, 09:48 PM   #1
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Problems with Cooper Discoverer AT3

Well, my truck is 10 years old and I've had the trailer for 6. The truck came with Michelin LTX A/S in 245/70/17. After 10 years and 106000 km (60 K miles) I was badly in need of new tires.

After lots of research, I decided on Cooper Discovers as my second choice, as Michelin Defenders are no longer made in my size. When they came in to my local shop, I got them mounted, drove it home, and several days later took off for the first trip of the year. They were filled 80 lbs in the rear, and 75 in the front. My Flagstaff is probably 7900 lbs loaded, and I use an Equalizer 4 point hitch with 1200 lb springs.

For the previous 6 years I would put the Ram in Tow/Haul, set the cruise at 100 km (60 mph), turn on the tunes and relax. This was not the case on this trip. Anything over 80 km (48mph) was downright scary. The truck would wander from side to side, tough to keep in one lane, and was affected by even small cars passing. I never got it over 93km without encouraging a heart attack.

For something that ran so good for so long on Michelins, what am I doing wrong? Could a slightly lower tire pressure, say 70 lbs all round, help the situation? Could probably run that without my TPMS warning.

I have not talked to my tire shop yet, as I just got back a couple of hours ago.
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Old 06-28-2020, 10:24 PM   #2
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I have those tires.

The tire shop that sold them didn't tell me they stink until I went in to complain and then it was too late for them to do anything about it.

Complain now.

For me they don't really wander. However, I've had issues with abnormal tire wear and shaking the truck. I've had it aligned two times and everything on the front is new I also l had to replace the tires on the front once already. The second set of front tires they sold me for half price and said it was probably a bad batch.. they were wrong. they all stink.
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Old 06-28-2020, 10:46 PM   #3
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We currently have at least 8 sets of the Cooper AT3 in use on farm and personal trucks. We like the price, performance, and longevity. As far as I know we have never had handling issues on the highway due to tires. They are quiet on the highway but are still aggressive enough when we are off the pavement. And we are constantly pulling some type of trailer.
I'm sorry you are having problems. I would take it back to a trusted tire shop with a good alignment service and tell them what is going on.
Let us know the outcome.
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Old 06-29-2020, 11:14 AM   #4
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Depending on the vehicle (and even same make/model/years are different) aggressive tread tires can cause wandering problems. Also excessive noise and strange wear problems. Most need to be rotated more often just to prevent the heel/toe wear on the tread elements in steering tires.

Like I said, all vehicles have their own quirks and aggressive treads can aggravate them.

I'd have an alignment check and have the "tech" pay close attention to suspension parts looking for excessive movement. A GOOD check involves two people, one moving the steering wheel back and forth with the vehicle on a solid surface while the other is underneath looking for movement in tire rod ends, ball joints, Idler Arms, and all other bushings used in securing the suspension parts.

ALSO

A good check of the bushings in the rear that keep the rear axle from moving around should be done at the same time. Rear suspension can steer the vehicle all over the road as well.
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Old 06-29-2020, 02:24 PM   #5
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My 2012 Ram 2500 calls for 60 lbs. front and 70 rear for FULL load. At 80lbs. in the front I would think you are riding on the center of the tire only and there isn't enough tire on the road to give you stability. Try dropping them back to the recommended pressures on the door and see what happens. My experience with Cooper has always been good, sorry for your pain.

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Old 06-29-2020, 02:55 PM   #6
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Tires

Quote:
Originally Posted by Devilscreekw View Post
Well, my truck is 10 years old and I've had the trailer for 6. The truck came with Michelin LTX A/S in 245/70/17. After 10 years and 106000 km (60 K miles) I was badly in need of new tires.

After lots of research, I decided on Cooper Discovers as my second choice, as Michelin Defenders are no longer made in my size. When they came in to my local shop, I got them mounted, drove it home, and several days later took off for the first trip of the year. They were filled 80 lbs in the rear, and 75 in the front. My Flagstaff is probably 7900 lbs loaded, and I use an Equalizer 4 point hitch with 1200 lb springs.

For the previous 6 years I would put the Ram in Tow/Haul, set the cruise at 100 km (60 mph), turn on the tunes and relax. This was not the case on this trip. Anything over 80 km (48mph) was downright scary. The truck would wander from side to side, tough to keep in one lane, and was affected by even small cars passing. I never got it over 93km without encouraging a heart attack.

For something that ran so good for so long on Michelins, what am I doing wrong? Could a slightly lower tire pressure, say 70 lbs all round, help the situation? Could probably run that without my TPMS warning.

I have not talked to my tire shop yet, as I just got back a couple of hours ago.
If they are 285/60/20 AT3 Iíll never have them again . They are hard to balance due to the weight, I had cooper replace 2 out of round . If you donít need an AT tire Iíve read many reviews continental seems to up there even with the AT tires.
I called cooper as per my tire shop, not an issue no money out of pocket. They gave me the 800#. I trailer a 38í 5th wheel no problems since all the tires are balanced properly and get rotated. Hope this helps.
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Old 06-29-2020, 06:25 PM   #7
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Those tires have slight crown built in by design to help reduce cornering wear that is prevalent in more aggressive tires. You need to be more attentive with the pressure adjustments. Try lowering them in 5 lb increments.
Hopefully that helps. I have them on a 1/2 ton running 55 psi. No issues, a little noisy but normal for a tread like that.
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Old 06-29-2020, 07:25 PM   #8
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Truck is at the shop now checking alignment etc. I had the first chance to drive it at speed without a load, and nearly went onto the shoulder once. I may try lowering them to 75 in the rear and 70 in the front which is where I kept my Michelins, if the problem is not corrected.
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Old 06-29-2020, 08:03 PM   #9
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I have those same Cooper AT3 on my 2018 Ram and tow 16K with no issues at all. The tires have worked great, wear is great, balance not a problem, both towing and solo the truck handles very well.
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Old 06-29-2020, 08:11 PM   #10
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I’ve heard a few issues recently about those tires. And from people that have had them before and liked them. That’s too bad as I was debating trying them out this fall when the stock tires will be done.
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Old 06-29-2020, 10:10 PM   #11
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I am like Daycruiser.

Mine are 295/70/R18 4080Lb load rating on a 2018 Ram 3500 CC, SB, CTD. Tires are quiet. I got 5 from Tire Discounters. Theyíve been rotated twice as of this morning and 10,000 miles. No noise no vibrations, good road handling, great looks, and very good on our farm. The wear so far look good and Iím demanding 60,000 miles. Weíll see if I get there. Tire sidewalls are noticeably stiffer.

Tire D repairs a flat last Friday. Patched it which I like. No charge. Massive screw went right through the tread.

Alignment has been good so far. I think a key must for any of these is rotation and proper alignment.

$1700 for 5 mounted, lifetime balance and rotation and 2 free alignments.

They better be good. When I hit 40,000 and they if they still are very good, I will be happy.
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Old 06-30-2020, 06:39 AM   #12
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Quote:
Originally Posted by NMWildcat View Post
We currently have at least 8 sets of the Cooper AT3 in use on farm and personal trucks. We like the price, performance, and longevity. As far as I know we have never had handling issues on the highway due to tires. They are quiet on the highway but are still aggressive enough when we are off the pavement. And we are constantly pulling some type of trailer.
I'm sorry you are having problems. I would take it back to a trusted tire shop with a good alignment service and tell them what is going on.
Let us know the outcome.
We have had them on for the past 3 years, same experience as NMWildcat.
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Old 06-30-2020, 09:26 AM   #13
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I put the Discoverer AT/3 tires on my F250 earlier this spring and Iím a bit uneasy with them. When I first drove my pickup home after the install I had a pretty bad vibration. I drove it for a week or so thinking maybe the vibration would go away. No dice. This all happened at the beginning of the Covid crisis and I had traveled about 25 miles one way to buy the tires from a guy I knew who had a Perfection Tire Shop. Once I decided to have the tires checked out I didnít want to drive back to the small store with very limited parking and waiting area. (Covid concern) so I went to my local Les Schwab store and paid for a Re-balance. They found one tire was defective and couldnít be balanced. Of course i then went back to the dealer I bought from and he replaced the bad tire no charge.

Now several months later Iím still not sure. Last year I towed my 7500 lb trailer with no sway at all. First trip out this year with the new tires I had a little bit of sway. Unfortunately I made several other changes to my set up so I canít be positive the new tires have anything to do with my new minor sway issue.

I find the tires are a bit noisy and it seems like I can feel the road more than with my previous tires. These new tires are way more aggressive than the OEMís I replaced. My one trip on snowy roads with them was great. Much better traction than the OEMís. (Steep driveway with limited ability to get a run at it)
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Old 06-30-2020, 09:39 AM   #14
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I have had 2 sets of Coopers that had very bad vibration and ended in tread delaminating as one long piece. Not sure if there are issues with the adhesives they use or if it is just poor quality control. Will never trust them again.
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Old 06-30-2020, 05:20 PM   #15
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Quote:
Originally Posted by Hatchdog View Post
I put the Discoverer AT/3 tires on my F250 earlier this spring and Iím a bit uneasy with them. When I first drove my pickup home after the install I had a pretty bad vibration. I drove it for a week or so thinking maybe the vibration would go away. No dice. This all happened at the beginning of the Covid crisis and I had traveled about 25 miles one way to buy the tires from a guy I knew who had a Perfection Tire Shop. Once I decided to have the tires checked out I didnít want to drive back to the small store with very limited parking and waiting area. (Covid concern) so I went to my local Les Schwab store and paid for a Re-balance. They found one tire was defective and couldnít be balanced. Of course i then went back to the dealer I bought from and he replaced the bad tire no charge.

Now several months later Iím still not sure. Last year I towed my 7500 lb trailer with no sway at all. First trip out this year with the new tires I had a little bit of sway. Unfortunately I made several other changes to my set up so I canít be positive the new tires have anything to do with my new minor sway issue.

I find the tires are a bit noisy and it seems like I can feel the road more than with my previous tires. These new tires are way more aggressive than the OEMís I replaced. My one trip on snowy roads with them was great. Much better traction than the OEMís. (Steep driveway with limited ability to get a run at it)
So the bottom line is they are a bit more noisy due to the tread being more aggressive, but that tread is a benefit when in the snow and yo need the traction.

Everything is a trade off, isn't it.
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Old 06-30-2020, 07:43 PM   #16
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So the bottom line is they are a bit more noisy due to the tread being more aggressive, but that tread is a benefit when in the snow and yo need the traction.

Everything is a trade off, isn't it.
No, the bottom line is that just like the original poster I am having new towing issues since changing to the Cooper tires. However I don’t have enough data yet to determine if my issue is the tires or a combination of the changes I have made. I also changed the trailer tires to Endurance LR E’s and ran 80 psi instead of the 65 psi in the previous Castle Rock LR D’s. And I added a 200 lb. topper to the truck. I’m heading out later this week for a short tow up the highway and I have changed my trailer’s psi to 65 as recommended with the Rocks. Hoping this will help with my new sway issue. No full water tank on this trip so again I won’t have the full data yet.

I only added the traction info to acknowledge that these Coopers are a more aggressive tread than my OEM’s. I had originally selected the Cooper HT/3 as they were similar to my OEM Continentals but the shop owner strongly recommended the AT/3 due to their better traction. (Snow country here)
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Old 07-01-2020, 06:38 AM   #17
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I also changed the trailer tires to Endurance LR Eís and ran 80 psi instead of the 65 psi in the previous Castle Rock LR Dís. And I added a 200 lb. topper to the truck. Iím heading out later this week for a short tow up the highway and I have changed my trailerís psi to 65 as recommended with the Rocks.

I strongly recommend not running the Goodyears at 65. Run them at 80psi, you will cause more problems by running them soft, you will heat them up, the sidewalls will flex more among other things. I went from Castle Rocks to Goodyears on my Rockwood and it made all the difference in the world but I ran the Goodyears at 80psi all the time. Run the AT/3 rears at max side wall pressure when towing and whatever the factory truck sticker says for the front. I am assuming you are using OEM size tires. The AT/3 are very good tires and have the same specs as the Michelin's with better traction.
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Old 07-01-2020, 08:30 AM   #18
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My Ramís sticker is 80 psi rear and 60 psi front.

I talked to my dealer about lowering the pressure. My dealer is a very experienced truck group mostly because they are small and sell to a bunch of farmers and horse folks.

They all recommend staying at the door sticker.

Tire Discounters sets the front @ 65psi which is what they perceive Cooper wants.

Iím staying w the Tire D since they are warranting the tires.
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Old 07-04-2020, 11:48 AM   #19
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I'd like to thank everybody who chimed in regarding my handling problems since mounting new Cooper tires. I am happy to say that the problem has been found. Seized lower left ball joint was causing binding then over correction from side to side. I also lowered tire pressure to 70 in the front and 75 in the rear. Truck feels totally normal again.

I am still happy with my tire choice as I live 3 miles off the pavement, so every errand sees 6 miles of gravel, not to mention that I live in Manitoba Canada, which often entertains 5 to 6 months of snowy conditions (at least very few tornadoes and no hurricanes).
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Old 07-04-2020, 11:54 AM   #20
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Thanks for getting back to us with the solution. We appreciate it!
As I mentioned previously, we have had excellent results with the AT3 Cooper's and I would have been shocked if it was the actual tire.
Glad your truck is back to normal. Enjoy!
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