Cooper Discoverer A/T3 megathread?

I got a question for folks. I have the 285/75R16 Discoverer AT3 XLTs. After the tire honeymoon ended (first 3-5k miles), i've noticed something that kind of bugs me. When accelerating or slowing from maybe 0-20 MPH, there is this rough feeling from the tires like you can feel the individual lugs of the tire vibration transmitting through the cabin. It isn't imbalance, the tires are perfectly balanced and very smooth at anything over 40MPH. It feels like a mud tire on take off and braking. Most of you will know what I'm talking about. My Falken Wildpeaks did it just slightly and the OEM tires were super smooth.

I believe it is due to the big open lugs and design. It's causing some buyer's remorse and wish I went for a tighter lug/less aggressive AT design since 99% of driving is on-road. I got these because they were an aggressive looking AT, but I don't think we can have our cake and eat it too...

 

I don't see an option for 265/75/17.

I like a skinnier/tall tire in the 255/75, but wasn't sure if it would impact traction in wet/snow conditions.

 

Shoot. I was thinking 265/70r17. Weird that they don’t have that size in the XLT.

 

having a super firm tire with that kind of feedback is one of the reasons i run these actually. if you are range E that's expected on a light truck. were your Falkens C or E?

 

It's your tire pressure, you're too low. Try doing a chalk test to set your pressure and rotate every 5k.

 

maybe or maybe not. i'm chalk tested and my pressures are dialed in. but my tires definitely exaggerate the feedback, because they are load E and under 31". hard little rocks with very little compliance. even 265/70-17's are far more compliant than mine (265/65-17 E).

 

You're right. I just don't think that these cooper xlt's have an aggressive lug pattern. They are pretty darn smooth and close together. I think his problem is pressure (or possibly alignment) related.

 

Any less aggressive and you will have a street tire.

 

I haven’t experienced this at all, mine are super smooth at all speeds. Check your tire pressure, that could be the issue

 

What pressure are you all running at? I've run between 30-35psi.

 

30F 29R psi warm on stock size E range.

 

This is 30 front warm chalk test



Rear landed at 28, still could go down a little, but I'll leave them a little over.

 

Wow, the ride is a lot better after dialing in from chalk test. Wish I didn't wait so long before. A couple psi makes a huge difference.

 

I can definitely see the tire wear spreading to the edges of the blocks now and it's all wearing. So I guess 30F/28R (warm) ~ 28F/26R (cold) is a good place to be with 285/75R16 ATR3 XLT on 8" wheels. I'll have to be a little more vigilant in colder months to keep pressures right.

Based on the charts and my calculations of the tires capacity at those PSIs, that still covers GVWR (5600lb) and then some; I never tow. Worst case, 28psi cold is around ~1850 load capacity per tire and 26psi cold is around 1750lb (TRA Light Truck Inflation Table chart). Collectively that's still 30% over GVWR cold.

 

From June, headed back to Kantishna in Denali National Park.

Kantishna-3594 by David Dawson, on Flickr

Kantishna- by David Dawson, on Flickr

 

Quoting for future reference.

Thanks @RangerComa

 

Hi guys, couple hundred mile follow up to lowering my tire pressures on my AT3 XLT from 32-35psi cold to 28f/26r (ends up 30-31 and 28-29 warm). Total game changer. For one, tires are definitely wearing on edges of tire for first time. Two, the takeoff and brake vibration is nearly gone and three, the ride is much better. I was honestly considering getting rid of these tires it was so bad. Now I'm good.

Don't take my word for it. Do the chalk test and then see what all of the Jeep guys (same curb weight) run on E tires. They all run ~28psi. For some reason all of the taco guys here seem to run mid 30s.

 

Ive noticed this as well. Ive always wondered what koolaid folks on here are drinking. I run what the door jame states on mine or a little less since theyre load range e.

 

I’m being lazy instead of reading through the 60 page thread.

Anyone know if they make Cooper Discoverer AT3 LT265 70R17 in C load instead of E?

 

@Synergy001 @Cavalry_PRO I bet @oscolivar1 reads this thread