Tyre wear - What's it telling me?

[KiwiNinja]

Been doing quite a bit of research into tyre wear (for the track) and how it relates to suspension and tyre pressures etc...bit of a black art I know!

I have attached photos of my rear tyre. On a CBR600RR with BT-016 tyres set to 31-32 front and back for which was a med temp day at Hampton last weekend.

From my (limited) understanding the mid section, that looks like a sandy beach, is what good tyre wear should look like. But as you go further out to the edge there is an amount of tearing. On the day it was torn up a medium amount but as I've done some commuting this week some of the excess has worn off.

The problem is that I don't have the experience to know what perfect tyre wear looks like. Bike handles fine...but then again I am pretty sure if someone, who knew what they were doing tweaked the suspension, it would handle even better.

Also regarding tyre cool down...if there is a 30-40 min break between track sessions would you treat the tyres as completely cold and therefore need warming up again?

Cheers in advance for any comments.

222729222730222731222732

[Gremlin]

I would say that tyre has worn quite well indeed. The treadlines are in good condition, I get worse wear on the road.

Depending on where the bike was parked during sessions, you can certainly get cold shearing, where the tyre isn't up to temperature and you're asking too much of it.

edit: one caveat is that you have commuted on it after the trackday, which has probably removed some of the story.

[Matt Bleck]

this helped me ....

http://www.onthethrottle.com/howto/dave-moss-unsprung-tire-wear/

[KiwiNinja]

this helped me ....

http://www.onthethrottle.com/howto/dave-moss-unsprung-tire-wear/

Yep just watching that now - that's where I got the sandy beach comment. Best vid I've found so far.

I would actually pay money for someone to teach me suspension 101, road setup, track setup but people with the right skill set are a bit thin in Auckland.

[NinjaBoy]

this helped me ....

http://www.onthethrottle.com/howto/dave-moss-unsprung-tire-wear/

and also this guide as well: http://www.crstuning.com/tire-wear.html

[White trash]

Really very dificult to tell from photos and as Gremlin pointed out, if you've commuted home, you're wearing off the evidence.

You should get Skidmark to show you how to get your knee down.....

[KiwiNinja]

Really very dificult to tell from photos and as Gremlin pointed out, if you've commuted home, you're wearing off the evidence.


Yeah I know. Next time I'll take photos through out the day.

[Sketchy_Racer]

That looks like what you should expect to see from a sports tyre on the track, the rubber is working just as it should.

Road tyres are designed to work in a large range of temperatures. I would take a couple of laps to let them warm up then you should be good to go have some fun!

[Mishy]

That looks pretty good to me. There is not a lot of real distress, and the rubber on the outer edge is really just a debri field - the used rubber moving away and collecting where you don't use the tyre hard for long.
It's pretty much what you would expect from a road tyre, and Hampton can be pretty tough on the rear tyre.
With 30 to 40 mins between sessions, the tyre would certainly be stone cold again if you don't use tyre warmers, and even with a road based tyre the warmers would extend the life - as well as letting you push the go button straight away :)

The big thing with something like a BT016 is that they are not designed to run at the same operating temp as a race tyre, so you won't do it much good if you cook it at 80 degrees all day.
If you have digital warmers, it would be better to set them a lot lower - perhaps 50 or 55 - and just keep them simmering between sessions :)

[Pussy]

BT 016s ball up a lot on my 750 on trackdays.... it's just what they do. Even with good suspension.
Personally, I really like them!

[Premature Accelerato]

Just to continue this tire thing. I recently spent a day at manfield running a new BT 002 ST on the rear of a gsxr 750. Day was around 15 degrees. I was not using tire warmers and had the rear set at 30 psi, took a couple of laps to warm up and then did another dozen laps. When I came in the tire was absolutely shredded. I was told it was cold tearing so next time out I dropped it to 28psi. Went out and did the same routine, came back in and the tire is still shredded. So, should I have dropped it even further. By the way, I have looked at the Dave Moss video, excellent information. Is there any truth to the story of being able to reverse rear tires to tidy them up, sounds a bit iffy to me.

[Biggles08]

Is there any truth to the story of being able to reverse rear tires to tidy them up, sounds a bit iffy to me.
Yes there is some truth to that but be aware that while you are 'tidying' it up it is slippery as all buggery (like you are riding on ball bearings). Once you have worked through the slippery patch the tires work fine again. This is true for Dunlop 211GP's at any rate, wouldn't know if road tires would work the same or not sorry.

[scorry]

Just watched the Dave Moss vid, he never goes back to his own bike to tell you why it was wearing funny (the bit where it isnt consistent around the tire) its at around the 48 min mark
That is pretty much what my 600 is doing, so can someone tell me why?

Thanks

[CHOPPA]

Just to continue this tire thing. I recently spent a day at manfield running a new BT 002 ST on the rear of a gsxr 750. Day was around 15 degrees. I was not using tire warmers and had the rear set at 30 psi, took a couple of laps to warm up and then did another dozen laps. When I came in the tire was absolutely shredded. I was told it was cold tearing so next time out I dropped it to 28psi. Went out and did the same routine, came back in and the tire is still shredded. So, should I have dropped it even further. By the way, I have looked at the Dave Moss video, excellent information. Is there any truth to the story of being able to reverse rear tires to tidy them up, sounds a bit iffy to me.

Yup works a treat. Most racers will turn there tyres around. I wouldnt turn a wet around though so I guess it depends on the tread pattern. If its a sports/race style tyre it will be fine

[scracha]

Cheers in advance for any comments.

Looks fine to me buddy. Last time I took a 6 hundy there it looked like someone had taken a cheese slicer and dragged it from the centre of my tyre to near the edge at regular intervals.

30 - 40 mins...yeah...I'd treat it as a cold tyre....but I'm a pussy. I see some riders start wiggling about and shit on warmup laps...I got told by a "guru" that hard acceleration and top speed is wot warms a tyre up so I try gassing it out of corners relatively hard on warmup laps.....dunno if that's right... :-)

[gatch]

I had read that it is the tire carcass flexing that creates the heat. Makes sense to me..

Though, is that correct ?

[steveyb]

I had read that it is the tire carcass flexing that creates the heat. Makes sense to me..

Though, is that correct ?

Typically that is correct, but of course is not the full story.
Heat is caused by friction, be it friction between solid surfaces rubbing against one another (e.g. tyre vs road), or by molecules clashing against one another as they are forced to move by something (e.g. a flexing tyre).
Flexion of the tyre causes the air (or nitrogen and anything else) that is inside the tyre to be squeezed and released thousands of times per second as the tyre rotates. The more flexible the carcass the faster and more extensive will be this sqeezing and hence the greater will be the rate and extent of heating. This is what causes the tyre pressure to rise as it heats up due to the expansion of a gas as it absorbs heat. Different gases expand at different rates and different amounts, hence the trend of using Nitrogen gas (N), to inflate tyres. No oxygen, no CO2, no water, just N, so you get one constant expansion rate.
Flexion of the tread area of the tyre also contributes to this heating (i.e. tread blocks on road tyres and rain tyres) in addition to their water dispersion and surface interlocking properties.
Spinning up tyres of course also creates heating by creation of increased friction, hence the formation of smoke (i.e. burning rubber) from a spinning tyre.
There will of course be a maximum above which the black body radiation and heat conduction of the tyre/wheel unit will match the heating provided but this will differ for any tyre/wheel combination and environmental temperature/weather condition.

[gatch]

Typically that is correct, but of course is not the full story.

Thanks for that. Makes sense.

Moral of the story. If you aren't using warmers, make the most of your "warm up" lap.

[Robert Taylor]

Thanks for that. Makes sense.

Moral of the story. If you aren't using warmers, make the most of your "warm up" lap.

Not entirely, the more specific the tyre is to racing the more carefully it has to be heat cycled. Not only prior to every race, but also after each race.

[Robert Taylor]

Just to continue this tire thing. I recently spent a day at manfield running a new BT 002 ST on the rear of a gsxr 750. Day was around 15 degrees. I was not using tire warmers and had the rear set at 30 psi, took a couple of laps to warm up and then did another dozen laps. When I came in the tire was absolutely shredded. I was told it was cold tearing so next time out I dropped it to 28psi. Went out and did the same routine, came back in and the tire is still shredded. So, should I have dropped it even further. By the way, I have looked at the Dave Moss video, excellent information. Is there any truth to the story of being able to reverse rear tires to tidy them up, sounds a bit iffy to me.

Many tyre problems are not the fault of the tyre itself Eg:

1) Is your tyre pressure gauge accurate within half a psi? Many are woeful

2) Are you adding air from a compressor source that is full of moisture leading to an abnormal pressure rise when hot?

3) What peak temperature are your tyre warmers actually heating the tyres to?

4) Is the suspension setup correct for your weight and the carcass construction and characteristic of the tyre you are using? MANY TYRE PROBLEMS ARE ACTUALLY CREATED BY INADEQUATE SUSPENSION SETUP. EVEN A HIGH END AFTERMARKET SHOCK HAS TO BE SPRUNG AND VALVED CORRECTLY

5) Are you monitoring track temperature and selecting compounds suitable for the conditions? If the track is cold are you lowering tyre pressures and firming up the settings to manipulate some heat into the tyres?

etc etc.......

[gatch]

Not entirely, the more specific the tyre is to racing the more carefully it has to be heat cycled. Not only prior to every race, but also after each race.

I'm using dunlop a12h, on an nc30. With forks and rs250 shock that your company has fiddled with.

[sugilite]

Interesting thread dredge. About the reversing tyre thing, if it has ripped (cold sheared), My experience is, that will only work if you catch the tearing before it gets to bad (bout only 3 to 4 laps worth on a superbike). Catch it in time (and it's easy to tell when it is happening during practice/qualifying) then reversing the tyre to rip it straight definitely works. If the tears have gone on too long/deep, throw the tyre away.