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I have a 16 RM, replaced stock Dunlop E3’s last year with E4’s. Brought it in for 20K service and dealer says rear tire is starting to show a little cupping at about 4K miles on the tire. After about 2k miles on new tires I noticed the rear tire jumps from 39psi to 50psi in under an hour, this is much faster than the E3 did, it would rarely climb that high unless I was riding hard in 85+ degree weather. Dealer says shock or riding too much straightaways might cause, but also said the shock seems fine.

Any idea on the issue, dealer said not likely to get any warranty support from Dunlop. Anybody ever get a tire replaced by the factory with similar issues?


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I have a 2018 roadmaster I bought new in 2019. I am just about to roll over 10k. I noticed some minor cupping on my rear tire while I was looking at my belt for wear. But it didnt look really bad to me. Maybe I need to investigate more. We did complete a saddle sore over memorial weekend so definatley long straight hard riding in temps around 100 degrees in west texas.
 

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cupping is usually caused by an imbalance. The rise in pressure would seem normal to me in the temps you are riding in.

Driving habits are also a cause braking to hard, overloading the bike. Improper air pressure can also cause it. There are others as you found out worn suspension parts can contribute. But since you have been told that the shock is good then maybe checking the balance might be next.
 

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I have a 16 RM, replaced stock Dunlop E3’s last year with E4’s. Brought it in for 20K service and dealer says rear tire is starting to show a little cupping at about 4K miles on the tire. After about 2k miles on new tires I noticed the rear tire jumps from 39psi to 50psi in under an hour, this is much faster than the E3 did, it would rarely climb that high unless I was riding hard in 85+ degree weather. Dealer says shock or riding too much straightaways might cause, but also said the shock seems fine.

Any idea on the issue, dealer said not likely to get any warranty support from Dunlop. Anybody ever get a tire replaced by the factory with similar issues?


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Tire could be out of balance. Just because the tire was balanced initially doesnt mean it stays in balance.
Ive always had cupping issues with my fronts especially on many different tire brands as well.
What was a game changer for me was to add balance dyna beads to my tires.
After adding these all the ills of tire wear went away. Because the tires are always in balance.
If you are sure your tire pressures have been correct and your suspension is dampening performing correctly then I would put those beads in.
I have not heard anything negative from anyone who is running them.
 

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Motorcycle tires cup eventually...every street bike tire I’ve had cupped. You hear all sorts of guesses about the cause, such as improper air pressure, etc. What causes cupping is the design of a motorcycle tire & the way it functions. If you’ll notice, the tread on bike tires run somewhat horizontally (or semi-horizontially) and not vertically (like on a car tire). This gives the section of rubber between the horizontial treads a leading and trailing edge. The leading edge strikes the pavement first and will wear faster than the trailing edge. As all the leading edges wear, they're now lower than the trailing edges. That’s what gives a cupped tire the scalloped look. If you replace bike tires when they start to cup, you’ll be buying lots of tires.
 

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I think that the recommended tire pressure is 41 which is where I keep mine at. Depending on the heat outside and the load I've seen them go 52. 6000 miles and no cupping.
 

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Hi! I want to buy roadmaster. Can someone help with the choice? Would be highly-appreciated.
Mariagrenier
Hi and welcome to you from New Jersey.
You will get a much better result if you put this inquiry in a separate thread rather then inserting it into this one.
Some might never see it based on the original topic.
 

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One other factor in cupping is the suspension. Do you keep your rear suspension at the recommended rates? If so, then I would suspect balancing or mounting incorrectly (not aligning the dot on the tire with the stem, etc.). If not, I would closely monitor your rear shock for any type of failure. It doesn't take much to rip a tire up.

My RM was a demo model and had under 4K on it. When I was taking the bike apart for paint, etc. over the winter (I only had it for 4 weeks), I noticed the rear tire was basically shot due to cupping. Bought new skins for the next spring and when I checked the shock, it had 0 pressure. Filled to the right amount and then checked it over the first long ride. It eventually went to zero again and the rear shock was shot and replaced under warranty. Ridden over 33K miles since and haven't had a single tire issue (41R, 39F).
 
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