Front tire, odd wear [Pilot Road II]

[Jacobien]

Heya!

Michelin Pilot Road II's are excellent. :ban: (Got that over with)

I've had the front Pilot II on now for what seems like 25,000km's which is exceptional. However, a while back I started noticing that there is severe vibration from the front at over 170km/h (on a track not the road )

I inspected the tire and found that the tread pattern going across the whole section of the tire is making bumps (difficult without pics).

If you look at the III's you will see that there is no more single tread line going across the whole section of the front tire - think this may be why.

So if you are experiencing vibration from the front at high speed AS WELL AS during hard braking, try inspecting the center tread of the front tire. :spank:

 

[ChevyFazer]

"bumps" on tires are usually caused by being under inflated for a long period of time

 

[Jacobien]

I believe that is the reason yes. Damn, I should have known cos the front is always the most at risk of under inflation. Anyway, I wanted to explain exactly what I mean by "bumps" so I made this pretty Paint pic. (15 minutes later)

The areas highlighted in red are the areas that are bumps.

Anyway, I am going to be getting Pilot Power front soon anyway and the Pilot II still gave excellent mileage despite poor maintenance.

 

[greg]

i had some vibration issues over 100mph on my last tyres, i think that a weight might have fallen off

no issues with my current tyres (bt-023's)

 

[YZF73]

Insufficient rebound damping is also a common cause of that type of uneven wear.

To check for this, after riding a reasonable distance to ensure the oils up to temp, bounce the front of the bike reasonably hard allowing it to return naturally, the forks should rise to the top, and then sit back to a resting position.

If the damping is insufficient the forks will continue to oscillate up and down, with damping rod forks your only option to really tune the rebound damping is by changing the fork oil viscosity.

Yamahaboyz

Sent from my HTC Wildfire using Tapatalk

 

[Jacobien]

May the rebound also be shot due to old fork oil? I am not 100% sure on the service intervals but I have never in 3years replaced the oil in the forks.

Anyway, I will check if a weight has fallen off that might be the culprit.

 

[Fishwiz4]

My front tire is beginning to do this as well (i do not have any vibration issues yet) and I was wondering if there is anything i can do to reverse this? i understand that running proper tire pressure should at least stop it form getting much worse, but is that the best i can hope for?

is the situation you are referring to the same as "cupping"?

my tire is a Avon Storm ST with only about 4000 miles on it.

 

[iSteve]

This is called cupping or scalloping tire pressure can slow it from happening but can't stop it. Some tires do this more then others.

It happens from braking. You can see how this happens by taking a pencil and pushing the eraser across a surface. The front part of the eraser will wear faster. This is like the tread of a tire. The front parts where the treads are cut will ware faster causing what appears to be scalloped tread blocks.

 

[YZF73]

May the rebound also be shot due to old fork oil? I am not 100% sure on the service intervals but I have never in 3years replaced the oil in the forks.

Yes, I should really have included that :spank:

It is recommended by suspension professionals to change your fork oil every 5000-6000 miles to maintain performance.

To give you a gauge of suitable oil weight, with 0.90kg/mm racetech springs, and 10W Putoline HPX oil, after riding the bike on the street the rebound is slow until the ambient temp is up to about 12 degrees C or so.

Yamahaboyz

 

[Jacobien]

Thanks yamahaboyz, think I will be replacing some fork oil then. On the cupping thing, I have had numerous instances where I braked really hard from high speed. I mean flat out from about 200km/h+, so that must have shortened tire life significantly.

I think a tire without the center tread will cupp slower. New Pilot Road III's do not have any tread in the middle anymore.

Think the official term is tread pattern percentage or something.

 

[616ah]

FWIW I found that the OE bridgestone BT020 I had cupped badly as it wore - on the cornering surface. I blamed it mainly on all the really small tread blocks flexing as they transmit force to the pavement (and wearing while flexed). I liked the continuous center rib though - no blocks there to flex on upright braking like your PR2 has (and no cupping there).

Not sure raising the tire pres is going to be helpful - by the time the tire is hard enough to reduce the tread feathering the way it grips the pavement is significantly compromised I think. Probably time to consider a different tire design if its actually causing a problem.

I too developed a shake near the end of the tire life - at the speeds mine was (110KPH+) I figured mine was either a balance issue from uneven wear or tire carcass issue - I didn't worry about it since the tire was nearly finished.

 

[PhotoAl]

Have had the same problem with PR2 fronts although mine is worse on the sides. My thought is the softer compound on the side of the tire is wearing faster than the center under hard braking and causes the "bumps". Run 32 to 34 PSI in the front. 34 to 36 when taking trips on the interstate. Can be felt easily by running your hand around the tire - feel the bumps? Now look at your hand - dirty isn't it! Time to go out and ride the dirt off.



My second PR2 front is nearing the end of life and will be replaced with a PR3 front.