Tread wear question

[OldNick]

OK. How to describe this. A couple of days ago I noticed a slight vibration from the front wheel at slow speed on smooth tar.

On checking the tyre, I can feel, rather than see, that the tread has worn so that the rear part of the large "islands" of the tread (circle) has worn more than the "tongue" of the tread (arrow) where ...a photo, you say? OK

Anyway. The tyre is a Michelin Pilot Activ rear tyre, put on the front wheel _not_ reversed_

My question is, what is causing that wear? Wrong pressure or not reversing the tyre? Or...?

Thanks for any help.

[Lee H. Mann]

G'day Mate !

That wear is called cupping.

Cupping can appear as soon as 5,000 miles and is not reversible.

There are several reasons for the cupping usually: Too little air pressure, too much air pressure, spirited riding on winding roads ....etc.

Those that travel Interstates do not experience the cupping as much as those who choose the back roads.

The front steering geometry is such that if you were to push your trike in a circle with the bars locked in one direction, and then push it backwards with the bars locked in the same direction, you would have 2 distinct paths that the front wheel would travel.

When cornering while riding the front tire is pushed and the harder you ride the more it is pushed across the pavement initiating a wear pattern.

That pattern will not go away and will continue to get worse the more miles you rack up. If you had a tire truing machine, you could true the tire and start anew.

We, in the states, also have this problem, but the Pilot still outwears the OEM tire so in some ways it is accepted or acceptable.

As far as reversing the tire's direction, I still do it for one reason. The tread direction of front and rear tires are opposing each other for wet road traction purposes. Many people don't do it.

[Jack Klarich]

A bit heavier fork oil can help stop front tire cupping also

Jounce your front end and see how much it takes for the rebound

If you have never changed your fork oil, now might be time JMO

[OldNick]

OK. Thanks very much for that.

I will raise the pressure a little (it's a couple low) and see if I can slow the cupping (I thought that may be what it was).

But there is still a problem....I LOVE the twisties!

My last tyre had a much harder tread and wore very well. But this one's comfort and corner sticky are way better so I will live with it.

Trouble is, it's so sticky I can all too easily lift the inside wheel....

[OldNick]

A bit heavier fork oil can help stop front tire cupping also

Jounce your front end and see how much it takes for the rebound

If you have never changed your fork oil, now might be time JMO

Ah...I have _changed_ to lighter oil, from 10 to 5. I find the ride far easier on the wrists. Railway lines and telecom humps in the road are no longer pucker-factor places.

If I go around jouncing my front end I might get arrested!

But yeah I will check it's rebound and see what I think. I can put more oil in as I deliberately left it low.

Trouble is with all this, it will take a long time to see what each change does...and then the damage is done. I guess if I learn on this tyre and just take the knocks, at least next time I will be better off.

[OldNick]

Hi guys. Just catching up on the thread.

Result. I found that the tyre was at 31 PSI . Not sure why: maybe grit ion the valve. IT has not done it again.

BUT, inerestingly, when I took it up to 38 PSI-ish, a lot of the tread inequality went away, like 80-90%. So AFAICS, rasing the pressure has mostly "fixed" the problem. I assume that being low allowed the tyre to "relax" and make it look worse.

Just FYI

[Jack Klarich]

Hi guys. Just catching up on the thread.

Result. I found that the tyre was at 31 PSI . Not sure why: maybe grit ion the valve. IT has not done it again.

BUT, inerestingly, when I took it up to 38 PSI-ish, a lot of the tread inequality went away, like 80-90%. So AFAICS, rasing the pressure has mostly "fixed" the problem. I assume that being low allowed the tyre to "relax" and make it look worse.

Just FYI

Funny thing about rubber as in tires and bushings, They always want to return to a relaxed position

This has plagued us in the alignment industry since the invention of the wheel

Good on you down under getting a hold of your problem

[OldNick]

Yeah I can imagine aligning stuff with malleable materials must be a bear.

Thanks for the good wishes, mate!