My tyres are weird - whats going on?

[HenryDorsetCase]

OK, so I did a trackday at Ruapuna a wee while ago (6 Oct). Bike went well but I wasnt feeling comfortable with the tyres all day. The morning was cold, and it got warmer as the day progressed. It was a really nice day. I started off with 30F and 30R cold and adjusted after each session. Got down to 27F cold (31 hot) and 28R (32 hot) during the day. I had a couple of weird rear wheel slides in the afternoon.

Check out these pictures. The middle to midlean of the tyres is nice and clean, slightly roughed up, and dull in appearance. Thats what I would expect. The "full lean" part of the tyre is black, shiny, and feels kind of sort of greasy.

Any thoughts as to why they aren't like the middle all the way round?

Obviously this is a street bike but still - thats all I have ever used on trackdays. My bestest tyres ever were the Dunlop Alpha 10s on the VFR400.

Also I am a terrible rider.

Metzeler Roadtec Z8's - new last year. Date codes 0721.

Anyway I am throwing it open to the ideas group.

[Jantar]

Not having had any experience with those particular tyres, my thoughts are slightly under inflated allowing the tyre to flex and get too hot.

[pzkpfw]

I'm dumber than rocks, but remember that the stock tyres on my bike were dual compound.

Harder in the centre to last longer on basic straight ahead movement, softer away from the centre for more grip when it's needed.

(I do remember that after a while they looked a bit weird to me, with the wear uneven across the width.)

A quick google didn't indicate that for these tyres, but seems possible?

[Grumph]

The wear pattern is about what I'd expect. Triumph is it ?
Ruapuna surface doesn't warm up till february. Ground water level is such that it's a cold surface even on a warm spring day.
Dropping cold pressure to get heat into the carcase only works to a limited extent with road tyres.

If you do another track day late summer on those tyres, I'd pick you'll be a lot happier with the grip levels.

[HenryDorsetCase]

The wear pattern is about what I'd expect. Triumph is it ?
Ruapuna surface doesn't warm up till february. Ground water level is such that it's a cold surface even on a warm spring day.
Dropping cold pressure to get heat into the carcase only works to a limited extent with road tyres.

If you do another track day late summer on those tyres, I'd pick you'll be a lot happier with the grip levels.

interesting - thank you for that. Now I think about that, the trackdays I have done in the past have tended to be Feb-Mar-April rather than October. I dont do the preseason Have a Go day that MCC put on because the one time I did it was freeezing cold and I havent cared to repeat it.

The bike is yet another naked middleweight - I have two functionally equivalent bikes - the Triumph Street Triple I have had for 10 years, and this is a 2014 Ducati Monster 1100. Aircooled, maybe 100hp at the crank, light and good handling.

The Triumph is better handling but I am putting that down to the suspension which has been upgraded by experts (and adjusted by a muppet).

Next time I am going to try and take one of those barbecue laser zapper thermometers to measure tyre temperature at the end of a session. I reckon that will be better than the old "how warm is it to the touch, and what pressure is in there" test.

Thanks.

[Hoonicorn]

It can take a while to adjust to new tires. Not knowing the track temp I'd have picked your front pressure was to low compared with rear, might have tried 30f and 25r to get more grip on the rear.
I'd assume in summer your using something like 28f and 22r.

And as said below, adjust the pace to the conditions.

[F5 Dave]

Slow down Rossi!


That said, I've crashed at Ruapuna by being offline trying to get around some whippersnapper for 3rd. When I got back to the pits I still had snow on my leathers.

[Kickaha]

Slow down Rossi!


That said, I've crashed at Ruapuna by being offline trying to get around some whippersnapper for 3rd. When I got back to the pits I still had snow on my leathers.

Ah yes, beaten by a GN once again, didn't you get run over as well ?

[F5 Dave]

Andy ran me over when I was riding the evil Joe the day before I think. No stinkin GN beat me. Ahead of me were Brendan and two CBRs with young versions of kids that got a damn sight faster with every return visit.

[HenryDorsetCase]

Andy ran me over when I was riding the evil Joe the day before I think. No stinkin GN beat me. Ahead of me were Brendan and two CBRs with young versions of kids that got a damn sight faster with every return visit.

The coolest bike at the trackday was a Husky Vitpilen 701. It had extensive work on the running gear and an Aprilia RS250 fairing, slicks. Really nicely done. They had sone some work to the motor and were using it as a test day. It was really quick through the infield but a bit less quick on the straights. Sounded cool too. Anyway, you should get one and employ me to ride it.

[Moise]

The Z8 has variable tension in the steel belt, reducing from the centre towards the edges. That might allow more movement of the tread at high lean angles?

https://www.forbesanddavies.co.nz/pr...sport-touring/

I did a tour in Oz on a BMW with those tyres. I had a couple of small slides from the rear, definitely not one of my favourite tyres.

Sent from my SM-S906E using Tapatalk

[husaberg]

The coolest bike at the trackday was a Husky Vitpilen 701. It had extensive work on the running gear and an Aprilia RS250 fairing, slicks. Really nicely done. They had sone some work to the motor and were using it as a test day. It was really quick through the infield but a bit less quick on the straights. Sounded cool too. Anyway, you should get one and employ me to ride it.

The Husky Vitpilen 701 would have to be one of the ugliest std bikes ever made.
My son races a 450Sm Yama YZ450F in the SM class and a dude has a 701 they both do 210 ish at the end of the straight at Ruapuna according to his husky speedo.
The 450's are far quicker through the infield though .
I have experienced weird shit with race tires at Ruapuna it seems to cold tear out the mid of the slicks even with warmers on seemingly warm days creating u shaped grooves.
I have spoken to Grumph about it it seems to be a Ruapuna thing. i think the answer is to do more meetings at levels as it a far more fun track on a lower HP bike and doesn't do weird shit with the tires.
Stop fafing about Get yourself A SM henry

[R650R]

Not having had any experience with those particular tyres, my thoughts are slightly under inflated allowing the tyre to flex and get too hot.

Plus one on this.

What are manufacturer recommended pressures Henry? Tyre tech has moved on for road tyres these days and I’ve been surprised myself at the higher recommended pressures. But according to people whose skill I respect that’s where they should be.
Think about it, you take same bike out on public road with likely less grip but at a track day we all decide to go ghetto and run low pressures???

[Grumph]

I have spoken to Grumph about it it seems to be a Ruapuna thing. i think the answer s to do more meetings at levels as it a far more fun track on a lower HP bike and doesn't do weird shit with the tires.
Stop fafing about Get yourself A SM henry

The last year we had a stinking hot spring and low groundwater levels at the same time, Steve Ward set a 125 lap time at the GP which i think has never been beaten. Arguably the 125's are the most tyre sensitive race class.

OTOH, Levels in midsummer drought conditions goes oily. It was not a very grippy surface when first laid and gets worse when it's very hot.

[HenryDorsetCase]

Bugger me. OK so like most blokes I have read the instructions AFTER I should have:

https://ultimatemotorcycling.com/201...0we%20listened.

38F 40R !!