Yamaha TRX850 Enthusiasts Forum

coxylaad wrote:i thought hot tear was deeper?

its a feckin mystery!

Life at Lean fella - mystery unraveled
https://lifeatlean.com/motorcycle-tyre-wear-guide/

Is it a dual compound tyre???
That may be the transition from the grippier softer compound on the outer section onto the harder compound closer to the centre ???

cobbadiggabuddyblooo wrote:Is it a dual compound tyre???
That may be the transition from the grippier softer compound on the outer section onto the harder compound closer to the centre ???

Racetec RR, yes it is: "Dual Compound rear"
http://www.metzeler.com/site/uk/product ... ec-RR.html

I posted the same question on a dutch forum and a guy with good knowledge (racer on national championship level and always helpful with questions like this) simply states: cold tear, lower the pressure.
I have to admit the tear did not appear just from the start of the day, but only after my laptimes were getting better.

Surprisingly, after my question and the guys answer, several people mention negative experiences with the Racetec RR, and that this type is very sensitive for pressure and geometry. They are known to (cold) tear very easily.

yep, which is what I was told also. That's how I ended up with such lower pressures.

In my experience Pirelli supercorsas are very sensitive to conditions, metzeler racetec (k2 rear and k0 front) were very good on my trx. I have no idea about the RR.

Found some unexpected action shots.

Tarwetijger wrote:

cobbadiggabuddyblooo wrote:Is it a dual compound tyre???
That may be the transition from the grippier softer compound on the outer section onto the harder compound closer to the centre ???

Racetec RR, yes it is: "Dual Compound rear"
http://www.metzeler.com/site/uk/product ... ec-RR.html



Surprisingly, after my question and the guys answer, several people mention negative experiences with the Racetec RR, and that this type is very sensitive for pressure and geometry. They are known to (cold) tear very easily.

I'd look at a geometry issue looking at the photos posted now that confirms my suspicions causing the cold tear, lowering tyre pressure will give more contact patch and generate more heat into the carcass to stop the tear, and treats the symptoms but not the cause.

If your geometry isn't right and your generating too much rear squatt in the suspension this energy is absorbed in the rear Spring and not the rear tyre which would give you less contact patch and less heat in the rear tyre.

With a steeper swing arm angle / more ride height this will generate anti-squatt, transmitt more of the energy into the rear tyre , which means more contact patch, more heat, to clean up the cold tear and more drive exiting corners.

Something else to consider.....
Spring rate may be at play too , as a too soft a spring will cause a similar problem and why setting sag is paramount right from the start to eliminate the Spring rate as the cause.

With the the correct Spring rate and sag to start and designated ride height for the track conditions, you get the desired squatt, this aids to keeping the bike tracking true exiting the corners with the bike not pitching further in the rear.
I'm sure Coxy was suffering the same fate with the yzf1000r swing arm fitted and the squatt issues it caused manifesting through the tyre.

Be mindful the other flow on issue if you have too much rear squatt, this will lift the nose when back on the gas and taking weight off the front end effectively increasing the rake and slowing down steering , also removing some of your front end grip to help keep the front end tracking true and which all together causes under steer on exit of corners...

Wot he said.