What causes the edges of the tread to cup on a bagger? I've tried 4 different brands of tires, tried aired to max, aired to hd specs and still cup. I check pressure often and even bought a new gauge. What am I missing?

 

It is indeed a common problem. Keeping the tire's pressure spot on helps, but doesn't stop it. Talked to the service manager, he has no idea.

Honestly, I think it's due to the fact that the swingarm isn't solidly mounted, but is allowed to move back and forth. The well-known "weave" or wobble is caused by the movable swingarm, and I think tire cupping, especially the rear tire, is related. And, how aggressively a rider rides may also play a part.

But, we're all just guessin'.

 

I never had a cupping problem with any of my older baggers ... Now, with the new frame ( okay old new 2009 ) I do ... Staying on top of the tire pressure helps.

 

Yup, keeping the tire pressure correct really helps.

Plus, I think I wear off the cupped edges as fast as they form. No chicken strips here.

 

Yep ... Pushing the corners helps to"feather out" the edges :>)

 

I've seen some bikes with really bad cupping. The raised edges are quite sharp. The cupping on mine is much, much, less noticeable, and the raised edges are much softer or more rounded off.

And, interestingly, it's much less noticeable on the Road Glide compared to my Super Glide. That's curious. Rode them both about the same.

 

I saw it on a my front directly behind the water gash. Never seemed to hurt anything. I doubt it's caused by anything except tread design.

 

Is is better to follow Harley's pressure spec or up it to tire max pressure?

 

If you have OEM Dunlops, then yes. Otherwise follow the recommended PSI from the mfg. I have Avons, so the PSI is higher.

 

I ran what Harley engineers came up with and checked often. Sure that is a compermize for handling first and wear second. They fill pretty hard at Harley's pressure. I now run Michelin and they run softer. My cupped tire was the other M guy. Three sets of Lopps never cupped.