Cooper Discoverer AT3 4S picking up rocks

I recently got Cooper Discoverer AT3 4S tires in factory size. The original Bridgestone Duelers were near the end of life and we had a puncture in one and it got driven on flat for a bit and ruined. This experience prompted me to look for something a little more rugged as we live back a 1/2 mile gravel lane. However, the new tires are picking up a lot of rocks. Driving in/out lane we hear continual clinking (I assume mostly on running board). When we get up to speed on the road, a few more tighter ones dislodge. We are starting to see damage in the plastic fender/wheel trim. We've also had some vibration issues, and occasional steering wheel shake. My son has a Crosstrek with Yokohama Geolander A/T tires. He recently rode with me for the first time since we got new tires and commented that the rocks sound bad. I asked if his car picks up rocks, and he said no.

Questions:

- do all A/T tires pick up rocks, or are some worse than others?
- can lodged rocks in tires cause vibration issues?

It looks like Cooper provides a 45-day Satisfaction Guarantee so thinking of going back to a highway tire ...

 

more examples or rock damage:

 

And another example of chips that occurred since new tires. Fortunately, we have pretty good mud flaps that seem to stop rocks from hitting the side of the vehicle.

 

I can see rocks like that on my Falken wildpeaks & KO2s as well. I guess it's normal for. A/T tires. This is why I never remove my mud flaps and always have full running boars / sliders with top plate.

 

Well with deep lugs on tires this is what you get.

 

In have Falken Wildpeaks on the 2011 and Nitto Ridge Grapplers on the 2018, both pick up rocks

 

I have General Grabber ATX and they pick up rocks too. I think it's just the nature of the beast with AT tires.

 

I've been pondering of a new HT tire with deep treads will have the same problem. It seems the rocks mostly get stuck in the cross groves. I suspect the rocks in groves that run longways around the tire are easier to eject.



Pondering if a new highway tire with deep tread will have a similar problem. Perhaps the main thing is the metal running board steps hanging down just sound really loud.

I looked at my son's Crosstrek tires (Geolander G015) (below) -- there are some rocks in it, but not nearly as many. Again, the metal running board steps may be what makes it sound so bad.

 

The bigger the tread, the bigger the rocks. You should have seen some of the boulders my Duratrac's would pick up. This is why I am trying to figure out fender flares and better mud flaps before getting MT's.

 

Both the factory Nittos and the Toyo AT3s Ive had on my 4R pick up rocks, as did the Nokian Rotiivas I had on my Taco. Just get 'er up to 50 or so and they will fling them out The ping, ping sound of gravel hitting the fender liners is a sign of a good trip...

Many ATs claim to have "stone ejectors" molded into the grooves. I haven't owned enough variety to know which work better...

 

Comparing some tread on other tires:

Cooper Discoverer HT3. There are not deep lugs on the side, so that would probably limit rocks coming out the side and chipping up the plastic fender liner, but there are still cross groves which would probably trap rock.



Dueler H/T D684 II -- original tires -- I only ran these for a few 1000 miles near the end of the tire life, so the tread was probably shallow enough they would not pick up rocks. Less cross groves than the coopers so rocks probably dislodge better.

 

In all fairness, HT stands for highway tire. They are not meant to be aggressive and used off road so it is natural they will not pick up as many rocks, nor as large of rocks.

 

I think the stepped treads on the Cooper AT3 are supposed to eject rocks:


Perhaps they do, but I think the cross treads tend to hang onto some rocks until higher speeds are reached.

 

Is this real life? Of course larger tread blocks pick up larger rocks. Coupled with minimal sound deadening you'll hear all of them being ejected

 

It's just the way AT tires are. Comes with the territory.

 

If the stones are causing damage and noise, you know the stone ejectors are working. They are not there to keep stones from getting caught in the tread, but to "eject" them as the tire turns at speed/rpm. If you choose AT tires, you choose tires that catch and hold rocks. It's just a choice, since you can't have better off road traction and have a tight closed tread pattern.

 

Yes, tradeoffs -- we are coming off minivans as our family left at home is now smaller, so we're learning -- thanks for all the input! We just never encountered anything like this previously with all-season tires, and it would not be a big deal if we did not live back a 1/2m gravel lane with perfectly sized worn gravel to stick in treads and had to deal with potential fender trim chipping every time we go somewhere.