Pirelli SC Question ... High Pressure's

[uncle_nospeed]

What up BARF'ers

Im hoping you could shed some light on a scenario that has happened multiple times with the same results.

Bike: 08 Yamaha R6(450)

When I run Pirelli Supercorsa SC DOTs or Slicks I constantly have to increase the pressure in the rear to clean it up (what looks like cold tearing). I know that the SC2s dont like the high track temps, because of the movement in the rear as the later laps came during the races.

When I started in the morning of Saturday, I had set the hot pressure around 26psi. From there I kept adding air until I got to 31psi where the tire finally looked good, and it was holding.

With Dunlops it is the complete opposite, the hot pressure I run with Dunlops is 19psi.

Anyone else experience this with Pirellis?

 

[rjbrittain11]

I constantly run my SC1 rear at 23-24psi. It always looks good. Could be your rear shock settings? What kind of rear shock do you have?

 

[uncle_nospeed]

I constantly run my SC1 rear at 23-24psi. It always looks good. Could be your rear shock settings? What kind of rear shock do you have?

Everything is stock, stock stock haha

I had it refreshed middle of last season, and had it set up at thunderhill.

 

[rjbrittain11]

I’m no suspension expert but I do know that when I had a stock rear it would shag the SC’s pretty good. My Ohlins set up properly now makes the tire look brand new no matter the weather or temperature.

So moral of the story: get a better rear shock

 

[jaybocc2]

if you have to add pressure to keep tire from tearing then likely the suspension is over working the tire or you're not being smooth on the throttle or both.

When was the last time the shock was serviced?

 

[uncle_nospeed]

I’m no suspension expert but I do know that when I had a stock rear it would shag the SC’s pretty good. My Ohlins set up properly now makes the tire look brand new no matter the weather or temperature.

So moral of the story: get a better rear shock

Haha Yeah thats the next move, its just weird that the Dunlops are the complete opposite

if you have to add pressure to keep tire from tearing then likely the suspension is over working the tire or you're not being smooth on the throttle or both.

When was the last time the shock was serviced?

Middle of last year, I dont think my inputs are jagged. I usually try to stay as smooth as possible.

If the suspension is overworking the tire then what setting would I have to adjust? Rebound?

 

[stangmx13]

more air usually makes tires more resistant to tearing in most conditions. usually, this sacrifices some grip as well... but that depends on how bad and where the tearing is.

without knowing more about your riding, springrates, valving, & geometry, its near impossible to suggest a fix for tire issues. get a shock built, then talk to your suspension and tire guy about it all.

 

[rjbrittain11]

Haha Yeah thats the next move, its just weird that the Dunlops are the complete opposite


Middle of last year, I dont think my inputs are jagged. I usually try to stay as smooth as possible.

If the suspension is overworking the tire then what setting would I have to adjust? Rebound?

How about we take away the guessing game...I have a really nice like new K-Tech rear shock that will eliminate this problem you are having. I'll sell it for a good price :thumbup

 

[easter bunny]

I'm by no means an expert but let me share my experience: I kept feeling the rear tire moving around and thought I was overheating it - liter bike at TH in triple digit temps. Added a few pounds of pressure.

Then I figured out I was getting cold tear from not having enough temp to heat up the carcass. I went the other way, lowered the pressure to get it to flex/heat more, and finally got the right temp all the way through and it hooked up great. It might be interesting to see what hot vs cold pressures are as a sign. You should get ~3psi difference.

 

[uncle_nospeed]

more air usually makes tires more resistant to tearing in most conditions. usually, this sacrifices some grip as well... but that depends on how bad and where the tearing is.

without knowing more about your riding, springrates, valving, & geometry, its near impossible to suggest a fix for tire issues. get a shock built, then talk to your suspension and tire guy about it all.

I will get one of the suspension gurus to take a look at what the bike is doing... thanks stang

How about we take away the guessing game...I have a really nice like new K-Tech rear shock that will eliminate this problem you are having. I'll sell it for a good price :thumbup

hahaha ... shoot me a PM, I might be interested

I'm by no means an expert but let me share my experience: I kept feeling the rear tire moving around and thought I was overheating it - liter bike at TH in triple digit temps. Added a few pounds of pressure.

Then I figured out I was getting cold tear from not having enough temp to heat up the carcass. I went the other way, lowered the pressure to get it to flex/heat more, and finally got the right temp all the way through and it hooked up great. It might be interesting to see what hot vs cold pressures are as a sign. You should get ~3psi difference.

I thought that was the reason as well, but when I lower it to get more heat in the tire... it starts to tear it bad

but not with dunlops, as soon as I lower the pressure in dunlops to get more heat it does what its supposed to. Clean it up while generating the heat the tire needs

Im just going to get the rear suspension looked at, because I am not trying to sacrifice grip

 

[easter bunny]

Are you using warmers?

 

[stangmx13]

lowering or raising the pressure a few psi doesnt affect the heat generated all that much. your inputs, ambient conditions, and the track have a much larger effect. this is moderately easy to notice as pressure changes with temperature. heres how:

set your rear tire at 26psi off the warmers, then do a session. do a fast in-lap and measure the pressure on the hot pit wall. in warm conditions with good pace, ull probably see ~2psi rise to 28psi. then wait for your tires to get back to warmer temp and reset the rear pressure to something else, 31psi for example. do a session and measure the track pressure again. the rise will likely be the same or very close, ~2psi. this means the tire gained nearly the same temp. an ok rule of thumb is 10degF for every 1psi. so even if the track pressures differ by 0.5psi, thats only 5degF.

of course, all that assumes you are gaining heat on track. cold tracks, slower riders, and/or underpowered bikes often don't gain any temp in the tires. in those situations, running higher pressures makes tons of sense.

lowering or raising the pressure does dramatically affect the carcass flex... and this is what you are changing to reducing tearing. you are trying to match the compound (tread rubber) flex with the carcass flex. every tire is constructed differently, so theres no rule of thumb for this one. the tire guys at race events know their stuff and usually have target pressures that work. of course, even those depend on your pace, setup, and ambient conditions.

 

[afm199]

So many things. My GSXR1000 with a Penske, set up by Canfield, never tears SC2s or SC1's. It does go through them quickly.
My GSXR 750 with a Penske set up by Canfield does tear them, and they still last a long time.

Why? Possibly because I run the 750 steeper than the 1000, and it's more likely to spin up the rear with more weight on the front. The 1000 is super flat and stable, and seldom spins up.

 

[DannoXYZ]

Try a little less rebound damping.

 

[Holeshot]

more air usually makes tires more resistant to tearing in most conditions. usually, this sacrifices some grip as well... but that depends on how bad and where the tearing is.

Not resistant to tearing, but less grip. The tearing comes from a grip/ slip issue. Adding pressure takes away grip/ carcass flex. When pressure builds, the tire has less grip...assuming the pressure set in the beginning was correct.

I'm by no means an expert but let me share my experience: I kept feeling the rear tire moving around and thought I was overheating it - liter bike at TH in triple digit temps. Added a few pounds of pressure.

Then I figured out I was getting cold tear from not having enough temp to heat up the carcass. I went the other way, lowered the pressure to get it to flex/heat more, and finally got the right temp all the way through and it hooked up great. It might be interesting to see what hot vs cold pressures are as a sign. You should get ~3psi difference.

Good thought. OP, start at the pressure Robert suggested. Neither him nor myself are tearing tires. What compound are you running? If you can get a pic, shoot CTracetires.com an email and see what they say.

OP: Call/ email Chris Maguire or Corey Neuer from CT Race Tires (Pirelli distributer). They have suspension resources as well (GP Suspension) techs that can help figure it out.

IMO, one thing it may be is using edge grip as drive grip. This is common when you hit a certain pace and aren't pointing the bike before pulling the trigger with a smoothish roll-on. Possibly...? You'll know if you're riding around with lots of lean angle at heavy throttle opening.

 

[stangmx13]

Not resistant to tearing, but less grip. The tearing comes from a grip/ slip issue. Adding pressure takes away grip/ carcass flex. When pressure builds, the tire has less grip...assuming the pressure set in the beginning was correct.

I don't understand what u are tying to say.

 

[Holeshot]

That's ok. I don't want to help you get ANY quicker...!

 

[jbawden]

I'm still trying to sort out cold tire pressure myself, lots of things factor in such as track temp, your pace, sorted suspension, and whether the tire is new or has laps on it.

I asked Chris at Pirelli and he explained a new slick has tremendous mechanical grip, so if you're not heading out on a hot track & ready to ride near race pace, a little more air should help keep the tire looking good.

As Berto said, more air reduces grip. Also, I think hot pressure is more critical if you're trying to find optimal grip (which you should be trying to do).

 

[uncle_nospeed]

I appreciate all the feedback and help.... I was out for the weekend so just now getting back to this.

Not resistant to tearing, but less grip. The tearing comes from a grip/ slip issue. Adding pressure takes away grip/ carcass flex. When pressure builds, the tire has less grip...assuming the pressure set in the beginning was correct.



Good thought. OP, start at the pressure Robert suggested. Neither him nor myself are tearing tires. What compound are you running? If you can get a pic, shoot CTracetires.com an email and see what they say.

OP: Call/ email Chris Maguire or Corey Neuer from CT Race Tires (Pirelli distributer). They have suspension resources as well (GP Suspension) techs that can help figure it out.

IMO, one thing it may be is using edge grip as drive grip. This is common when you hit a certain pace and aren't pointing the bike before pulling the trigger with a smoothish roll-on. Possibly...? You'll know if you're riding around with lots of lean angle at heavy throttle opening.

I try to be as smooth as possible, but I am getting on the gas a lot sooner as I ride a crippled R6. I am slowly getting comfortable adding throttle while leaned over.
I am beginning to think that I am overriding the stock suspension. I ran 1:59s at buttonwillow AFM rd2.
I was running Pirelli V2 SC2's front and back.

I'm still trying to sort out cold tire pressure myself, lots of things factor in such as track temp, your pace, sorted suspension, and whether the tire is new or has laps on it.

I asked Chris at Pirelli and he explained a new slick has tremendous mechanical grip, so if you're not heading out on a hot track & ready to ride near race pace, a little more air should help keep the tire looking good.

As Berto said, more air reduces grip. Also, I think hot pressure is more critical if you're trying to find optimal grip (which you should be trying to do).

O I am... I dont get it with Dunlops. I may have to try Slap on a pair of Dunlops to see if they do it now since my pace has increased.

 

[stangmx13]

That's ok. I don't want to help you get ANY quicker...!

meh. I had a paragraph typed to disagree with your post. then I realized I didn't know what u were trying to say.

tearing is not always caused by grip & slip conditions, which is why adding air can make a tire more resistant to tearing.

I'm still trying to sort out cold tire pressure myself, lots of things factor in such as track temp, your pace, sorted suspension, and whether the tire is new or has laps on it.

I asked Chris at Pirelli and he explained a new slick has tremendous mechanical grip, so if you're not heading out on a hot track & ready to ride near race pace, a little more air should help keep the tire looking good.

As Berto said, more air reduces grip. Also, I think hot pressure is more critical if you're trying to find optimal grip (which you should be trying to do).

cold pressure is borderline useless. u must record tire temp when taking cold pressure and u must correlate the two, otherwise u are just guessing at how much air is actually in the tire.

hot track pressure is the most useful as uve said. it doesn't give the complete picture, but its pretty close.

warmer pressure is a great starting point as it mostly sets the tire temperature.