Tyre wear at VMCC Rd 2

**Deano** · 25th June 2009, 13:01

Despite only riding a commuter SV650, I managed to chew out a rear tyre in just one weekend. This included 2 qualifying and 4 races.

The wear looked like nothing I have encountered before and despite fiddling with suspension set up, it did nothing to reduce wear.

I noticed a lot of other racers were talking about tyre issues and wonder if the cause was cold shear ?

Can anyone else add any info to this ?

**TonyB** · 25th June 2009, 13:06

What tyres are you using? If your using Pirrelli SC0 compound, my understanding is that its designed for hot weather, and you are actually better with the harder SC2 when its cold.

Have you checked your shock linkage for wear? My bike chewed out a tyre in record time, mostly because it was an SC0 and because the linkage had some slop, meaning there was about 8 to 10mm of freeplay when the back end was lifted.

**Deano** · 25th June 2009, 13:09

Originally Posted by TonyB

What tyres are you using? If your using Pirrelli SC0 compound, my understanding is that its designed for hot weather, and you are actually better with the harder SC2 when its cold.

Have you checked your shock linkage for wear? My bike chewed out a tyre in record time, mostly because it was an SC0 and because the linkage had some slop, meaning there was about 8 to 10mm of freeplay when the back end was lifted.

SC2 on the rear. We replaced the spring for a stiffer one at lunchtime and the linkage seemed fine.

**scracha** · 25th June 2009, 13:14

You know what I tight-arse I am Deano...I did the whole series on one set of GPR-A10's last year. The first race on Sunday did more wear to my tyres than the whole of the series last year. Normal wear on Saturday and in the final race when it was a lot colder.

**Shaun** · 25th June 2009, 13:28

Originally Posted by Deano

SC2 on the rear. We replaced the spring for a stiffer one at lunchtime and the linkage seemed fine.

The track was very cold, causing some of these issues. Check your Pirelli for the manufacuring date on the side wall, may have been an Old model type, which will shred very easy- due to so many temperature flucuations

**johan** · 25th June 2009, 15:42

Do you have any photos of your tyre Deano? I'd be interesting to see.

It seems to be a hit and miss. I saw brand new tyres shredded to pieces after two sessions, others looked just scrubbed in after the whole weekend.

With my bike running Pirelli sc2 superbike slick, lower pressure gave me better wear.
~24psi cold, ~30psi hot after a race, around 85 C surface temperature.

The rider on the 749 tried similar settings, it didn't work at all for him, but he might have had a softer compound though.

I have a rate 8 spring, he's got a 12, if I remember correctly.

My rubber was an early 2008 batch, used 3 race meetings, its retired now, but looks mint.

I don't know if any of this helps you Deano, it's all very confusing, so many variables.

**Biggles08** · 25th June 2009, 16:07

My tires seemed to last ok throughout the weekend. I was wearing METZELER 'Dot' Racetechs K1 front and K2 rear. I did encounter some cold shear on the saturday but reduced the pressure and it cleaned up a bit after this. I was stoked at the amount of grip I was getting considering how cold the track was!

**scuzeme** · 25th June 2009, 16:08

Hi Deano

I know i wasnt pushing it as hard as some others but i had a Metzeler K0 (qualifying tyre) front and a K1 Rear which had done one race at Taupo and a test day, these were a little chewed but still good, i changed to a brand new K1 front and K2 rear on Sunday and Robert came and made a few changes to my suspension and they are still mint. Robert did make a comment that hed seen a few tyres looking a little worse for ware on Sunday.
I was running 28 psi Front and 29 psi Rear in my tyres and checking them before and after every race after having my spill on Friday.

My understanding (and its probably a bit simple) is that cold shear happens in cold conditions when the tyre hasnt had time to warm up to proper operating temperature, cold shear can be eliminated sometimes by making the tyre work harder quicker through suspension and tyre pressure changes.

I may be a bit off with this though.

Cheers.

**Deano** · 25th June 2009, 16:34

Cheers for the feedback guys.

I was running 27psi rear and 30psi front while on the warmers. (24 and 27 cold respectively)

I haven't encountered this much wear before. Will try and get a picture up soon....like when Drew returns my bike !!

**mossy1200** · 25th June 2009, 16:50

Race 2 was as far as my rear got and had to be changed for race three.medium compound pirelli rear.I was under the impression cold sheer was caused by having tyre running to hot on a cold surface so harder tyres required so the differential was not to great.Run them to soft and the problems increase.

**neil_cb125t** · 25th June 2009, 17:25

hey mate,
i am running the dunlops had sim problems on the friday test day - rob taylor modded a fews things - aye dropped the shit out of my pressures from 28 cold on the rear to 25 hot!! check out the pics the back end looks flat as!!
Also added alot of preload on the rear - was told a heavier spring may help. I practiced and raced the first 6lapper and then the 10 lapper on sunday ( in 2 classes ) then both sides had worn ALL the rubber!!! the right looked like shit though.

i cant believe i did 32 laps racing and 2 practices on a new dunlop!!!

I was running 27psi rear and 30psi front while on the warmers. (24 and 27 cold respectively)

I haven't encountered this much wear before. Will try and get a picture up soon....like when Drew returns my bike !![/QUOTE]

**Sparky Bills** · 25th June 2009, 18:09

I had Pirelli Supercorsa's... SC0 Front, SC2 Rear.
Running 26psi (cold) front and rear.
10kg rear spring, 94kg rider.

Mine were mint all day! Started moving round a little towards the end of races, and were starting to chew a little but nothing to worry about really.
Would even be tempted to use them for round 2.
Will have to consider my budget though.

Eamon had massive issues with his. They were destroyed before Saturday had ended!

Cold track temps didnt help.

**Biggles08** · 25th June 2009, 20:05

Originally Posted by Sparky Bills

Would even be tempted to use them for round 2.

You Should Sparky...you should....help me keep up!

**Robert Taylor** · 25th June 2009, 20:36

Some very valid points, the long track is like adding a different track as the tyres spend so much of their time on their sides. For parts of the track you need a soft spring with lots of preload, for other parts a firmer spring with less preload. And then theres damping......Its all compromise in the end event. Bring on electronic shocks that self adjust for every corner!!!
Shaun made a valid point about the age of the tyres, some may be 3 years old when you buy them new and stored in less than ideal conditions with temperature fluctuation. Why are many race tyres sold cheaply?
The Europeans dont usually race in such cold temps and dont experience cold shear to anything like the extent we do.
Because of all of the above its probably fair to say that the odds are stacked against us and that everything we do to race in such conditions is almost a band aid.