Tire Life Question

Started by supercarl, July 17, 2012, 11:34:00 AM

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supercarl

Well the reason I was asking this question was because I was doing 19 races in one weekend. 8 sprints on saturday then a GTU, two 9 lap ASRA races, and 8 sprints on Sunday. Plus the morning practices.

Doing so many races, I didnt really have any time off for tire changes. I just had to run what I could put on in the morning or during a lunch break. So I was wondering if I was just going to hit a complete drop off somewhere with the tires or something. I ended up making one set of tires last all 8 sprints the first day, then I used a rain set sunday for GTU & two sprints and then put on a new set of DOTs for the last 8 races. I wanted to win all my races in amateur. so I was running 1:14 -1:15 pace or so. But to answer your question, I always want to go as fast as I possibly can lol. Dont know what you mean by margin of safety...

Suprisingly I didnt really have any issues that weekend tho. I felt the rear sliding a little more and more as the day wore on, but it wasnt anything crazy. I still managed to put down good times. That being said I still dont know how to gauge tire life accurately because I was still putting consistent times down after 7 races when the tire shouldve been worse off haha. I figured I'd need new tires if the lap times were slower, but that was never the case. I felt comfortable on them all day. Only reason I replaced the tires is because I hit the wear markers.

However, I know other riders that swap tires well before that mark so it just leads me to believe that Im not changing tires eneough and thus not getting the best possible performance for the best possible lap times. With my original post I was just trying to get a reasonable answer on after how many laps/races it took before a tire lost eneough life for me not to really get my best times on it. I know obviously replacing the tire every race would be ideal but thats just not feasable. I was looking for a more realistic answer like 4 races on the rear, 8 on the front, etc... Although I realize now that there is no definite answer as it depends on so many factors.

Maybe just asking how often the fast guys change their tires on a 600 at blackhawk wouldve been easier haha  ::) 
Super Carl Soltisz #620 facebook.com/supercracing
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Super Dave

#13
Quote from: supercarl on July 31, 2012, 11:07:14 AMSo I was wondering if I was just going to hit a complete drop off somewhere with the tires or something....I wanted to win all my races in amateur. so I was running 1:14 -1:15 pace or so.
Weren't you running 12's and 13's before in some races?

Quote from: supercarl on July 31, 2012, 11:07:14 AMBut to answer your question, I always want to go as fast as I possibly can lol. Dont know what you mean by margin of safety...
Well, it's pretty simple.  How much will it cost to fix the bike if you throw it down in T2?  How much money do you loose in entry fees by not racing in races you paid for?  How much in contingency money do you loose by finishing a position back when you go from 12's to 15's?

And how much is a rear tire? A front?

For the cost of a crash, you could probably buy two rears and a front.  Could you do 12's all the time having better rubber?  Could you explore your riding and your set up to put down 11's with more consistent rubber? 

Quote from: supercarl on July 31, 2012, 11:07:14 AMI was still putting consistent times down after 7 races when the tire shouldve been worse off haha. I figured I'd need new tires if the lap times were slower, but that was never the case. I felt comfortable on them all day. Only reason I replaced the tires is because I hit the wear markers.
Most likely, because it sounds like you're on a tight budget on tires, your chassis is set up for grip of a used tire.  So, you're not getting the full advantage of a new tire.  A new tire with lots of traction will load up the chassis more and cause it to react a certain way.  But if you then migrate or remain on old rubber, then your set up becomes that. 

Or it takes you time to relax. 
Super Dave

supercarl

I got into the 13's, but not the 12's yet. Hoping to hit that next weekend!  :cheers:  I was just using 14-15 as an average.

But I see what your saying with the cost of everything. The issue for me is not actually cost of tires. Im doing well enough now that I have plenty of tire money so Im not super budget constrained like I was before, but I still dont want to throw away money on tires if I dont need to. The issue for me is just understanding that fine line of when to change tires so I'm not doing it early and being wasteful or I'm not doing it late and risking a crash/slower laptimes. I just need a better feel for reading my tires. Im sure it will become more aparent as I get faster. I think I'm just too slow now to have a good idea  ::)

As far as chassis set-up, what kind of things do you do to adjust for new tires vs old? Im thinking that if I dont have time to change tires throughout the day I should maybe adjust settings to account for tire wear between races. It would also be beneficial to know how to set up for new tires so I could get fast laps on the important races. I assume just run it a little stiffer?
Super Carl Soltisz #620 facebook.com/supercracing
Sponsors: Michelin, Sportbike Tire Service, TSE, Nexx WrecksNRestorations, Vortex, Moto-D, Pop Shadow, Galfer, Spy, Armor Bodies, GoPro, Sidi, AGV Sport, MotoNation, Hindle, Motion Pro, Zero Gravity, Bernat PC, GP Tech, & All Balls Racing

Super Dave

Are you working with TSE yet?  Start.

Money on tires is never thrown away.  If you use them less, you can sell them to someone because they might still have some real value to someone else when they're not shot.  If one's focus was on getting faster and faster, without budget constraints, then you'd go out every time on new tires.  Period.  Because then you'd build a set up based upon excellent traction, and, when it does let loose a little, it's still driving forward. 

Often, when you run your tires down too far, there so little rubber that the issue is keeping heat in the tire.  So, you start your race after the tires being on warmers for whatever period, then they loose heat during the race because there isn't enough insulation to keep heat in.  The tire drops below the temperature it is supposed to function at, and the performance drops off.  Often, that isn't so bad on a "track day" tire as it is thicker, thus holding heat in because the "blanket" is thicker.  Materials of construction are another issue, but keep this simple. 

So, "making it stiffer"... 

A spring has a rate.  You really don't make it stiffer.  You might compress it, and that starts the travel in a different place.  Compression and rebound...that's more about speed of compression or rebound.  If those are overcoming the spring rate, then you've got problems all their own.

Let's say you've got the right spring for new tires.  New tires are going to generate more traction loads than used.  Thus, the new tire is going to compress the springs with that traction load, be it braking, accelerating, or turning...or all of them together.  As the tire wears, it won't generate that load.  Then the rate of that spring can be too much, and the worn tire spins too early.  When the tire spins, it releases the compression of the spring...and that alters geometry under load.  That affects your steering, weight distribution, consistency, ability to save it when it gets strange...
Super Dave

supercarl

Quote from: Super Dave on July 31, 2012, 03:23:50 PM
Are you working with TSE yet?  Start.

Thanks for the advice. I'll talk with the TSE guys this upcoming weekend and see what I can learn.

Quote from: Super Dave on July 31, 2012, 03:23:50 PM
Money on tires is never thrown away.  If you use them less, you can sell them to someone because they might still have some real value to someone else when they're not shot.  If one's focus was on getting faster and faster, without budget constraints, then you'd go out every time on new tires.  Period.  Because then you'd build a set up based upon excellent traction, and, when it does let loose a little, it's still driving forward. 

This is pretty helpful. I'm slowly starting to understand tires more and more. Based on what you said I think my new plan will be to replace tires every chance I get during a race weekend. Then I can just sell tires that still have life left or use them for practice/trackdays. If contingecy dries up that may change though haha. Hopefully by running new tires more often I can get a more consitsent set-up and feel.

Quote from: Super Dave on July 31, 2012, 03:23:50 PM
So, "making it stiffer"... 

A spring has a rate.  You really don't make it stiffer.  You might compress it, and that starts the travel in a different place.  Compression and rebound...that's more about speed of compression or rebound.  If those are overcoming the spring rate, then you've got problems all their own.

Let's say you've got the right spring for new tires.  New tires are going to generate more traction loads than used.  Thus, the new tire is going to compress the springs with that traction load, be it braking, accelerating, or turning...or all of them together.  As the tire wears, it won't generate that load.  Then the rate of that spring can be too much, and the worn tire spins too early.  When the tire spins, it releases the compression of the spring...and that alters geometry under load.  That affects your steering, weight distribution, consistency, ability to save it when it gets strange...

I understand the spring rate and the fact that new tires are going to generate more load, but I'm unsure on the adjustments for compression and rebound with the new tires. From what Ive gathered it appears that with newer tires you would want to go in with compression and rebound while you would go out as the tires are gettting used due to less traction. Is this a correct statement? does it vary on the forks vs the rear shock? Right now I have the sag and preload set on my bike for me. Spring rate is also correct for my weight. Ive tried adjusting compression and rempound before but Its hard for me to notice the results.
Super Carl Soltisz #620 facebook.com/supercracing
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Super Dave

Quote from: supercarl on August 01, 2012, 08:50:44 AM
Thanks for the advice. I'll talk with the TSE guys this upcoming weekend and see what I can learn.
Talk to Scotty.  Tell him Super Dave sent you.  Talk.  Build a relationship.  It's gonna be twenty questions all the time, but you'll learn in the process too.
 
Quote from: supercarl on August 01, 2012, 08:50:44 AMBased on what you said I think my new plan will be to replace tires every chance I get during a race weekend.
Fresher's faster!
 
Quote from: supercarl on August 01, 2012, 08:50:44 AMRight now I have the sag and preload set on my bike for me. Spring rate is also correct for my weight. Ive tried adjusting compression and rempound before but Its hard for me to notice the results.
Well, first, what the heck is "sag and preload set on bike for me"? 

Spring rate is a thing.  Yes, there's a window.  But sag is a tool.  Using it as a concept of "I run it at 35mm" is not correct.  While you might have a set up for Blackhawk, I wouldn't directly run a Blackhawk set up at Road America.  T6 creates some specific problems in addition to the corners being fast.  One can get real results by changing sag settings. 

At some places, a spring rate change is good too. 

These are some things Scotty can work with you on. 

10's and 11's...  Look towards those.  :)
Super Dave

supercarl

Quote from: Super Dave on August 01, 2012, 12:22:35 PM
Well, first, what the heck is "sag and preload set on bike for me"? 

Well at the begining of the season at RA the Turn one guys helped me set the sag/preload on my bike. You know, measuring forks both on and off the bike and then setting it correctly etc. I didnt realize that you were ever supposed to change it though. I thought once you set it for your weight you just leave it alone. Just one more thing I need to mess with now haha  ::)

Ill def talk everything over with TSE at the track though and let em know you referred me  :cheers: . Im sure it will help alot. I'll have this suspension stuff mastered one day haha
Super Carl Soltisz #620 facebook.com/supercracing
Sponsors: Michelin, Sportbike Tire Service, TSE, Nexx WrecksNRestorations, Vortex, Moto-D, Pop Shadow, Galfer, Spy, Armor Bodies, GoPro, Sidi, AGV Sport, MotoNation, Hindle, Motion Pro, Zero Gravity, Bernat PC, GP Tech, & All Balls Racing

Super Dave

Quote from: supercarl on August 01, 2012, 12:58:14 PMJust one more thing I need to mess with now haha  ::)
Don't worry, the longer you involve yourself in this, the more things you mess with approaches infinity...  :)

Quote from: supercarl on August 01, 2012, 12:58:14 PM
Ill def talk everything over with TSE at the track though and let em know you referred me  :cheers: . Im sure it will help alot. I'll have this suspension stuff mastered one day haha
Mastering is hard.  Just try to find a handle to hang onto it.  :)
Super Dave

supercarl

Alright new plan. Im going to go really really fast and get a factory ride so a pit crew can do it all for me :D haha if only.
Super Carl Soltisz #620 facebook.com/supercracing
Sponsors: Michelin, Sportbike Tire Service, TSE, Nexx WrecksNRestorations, Vortex, Moto-D, Pop Shadow, Galfer, Spy, Armor Bodies, GoPro, Sidi, AGV Sport, MotoNation, Hindle, Motion Pro, Zero Gravity, Bernat PC, GP Tech, & All Balls Racing

Super Dave

Quote from: supercarl on August 01, 2012, 03:22:57 PM
Alright new plan. Im going to go really really fast and get a factory ride so a pit crew can do it all for me :D haha if only.
Gotta have goals...  Don't let yourself stand in the way of you shooting for the stars.  It's not easy, and you might not get all the way there, but the journey has some pretty sweet scenery...
Super Dave

supercarl

Well said! I'm taking the scenic route  :biggrin:   :cheers:
Super Carl Soltisz #620 facebook.com/supercracing
Sponsors: Michelin, Sportbike Tire Service, TSE, Nexx WrecksNRestorations, Vortex, Moto-D, Pop Shadow, Galfer, Spy, Armor Bodies, GoPro, Sidi, AGV Sport, MotoNation, Hindle, Motion Pro, Zero Gravity, Bernat PC, GP Tech, & All Balls Racing

alocker

Quote from: supercarl on August 01, 2012, 03:22:57 PM
Alright new plan. Im going to go really really fast and get a factory ride so a pit crew can do it all for me :D haha if only.

I saw few guys helping you out last weekend.  Don't take that for granted, my wife finally figured out how to put my front stand on after 2 yrs :biggrin: The next goal is training her to turn the Gopro on and off. 

Dave pretty much said it all.  You will never know the exact time to change tires.  You can either jeopardize a few dollars by changing too soon or jeopardize a lot of dollars and your safety by changing too late.  Depending of if Joe is racing or not, you can buy him lunch and he might be able to give you a hand at a fast tire swap. 
MW AM #454