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Old March 9th, 2018, 10:23 AM   #1
agnt_kruger
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tire question

I am getting back into riding after a hiatus, had kids and the whole deal. I finally have a place to properly work on bikes so I decided to get back into the sport I love. Anyways I will be doing my first track day in a few weeks. I picked up a newgen with very low miles and it has some Dunlop GT501s that are probably 80% left, and no wear on the edges since the person didn't lean at all. I purchased some new super sticky Bridgestone RS10s and I am contemplating putting them on or not. If you were me would you run through the tires on there first? Or use the better/track suited RS10 tires. I probably wont be leaning that far over anyways given I have a lot of work to do since I am rusty. Would it be better to use the GT501s now, or later when I have more experience? Or not use them at all? I watch a lot of Ari hennings videos and he says sport touring tires have more than enough grip to get a full lean on. All tho I would like the best experience possible and the most safe experience possible which is leaning me towards putting on the Bridgestones. Any insight from you guys would help out a lot.
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Old March 9th, 2018, 10:32 AM   #2
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I'd absolutely mount the new tires.

No question.

If they were original tires from 2011, I wouldn't even ride on the street with them - no matter how much tread they had left.
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Old March 9th, 2018, 10:35 AM   #3
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got it, will do, I appreciate the response. Mounting this weekend
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Old March 9th, 2018, 11:06 AM   #4
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the feel of the new tires will be so much better that the other ones a not worth it.
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Old March 9th, 2018, 01:21 PM   #5
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I'd mount the tires too. But here's some food for thought:

1) If you've never done a track day, your pace will be a lot closer to street-normal than flat-out. So the 501s, while not great track tires, would probably not hold you back if they're in good shape. Short answer is that you're not going to be pushing the bike very hard on your first day. It'll feel like you are, but trust me... you won't be.

2) Reading between the lines of your post re the previous owner, those tires (especially the rear) might be a bit squared-off. You may notice this, since you'll be spending a lot more time leaned over. It's not a big safety issue at beginner pace, but it's not ideal.

3) Check the tire manufacture date code (4 digits, first two are the week of the year and the last two are the year, i.e. 1405 is week 14, 2005). If it's more than five years old, time to replace the tire even if it isn't worn. But less than that, it's still got useful life. Obvious weathering issues like hardened rubber, sidewall cracks etc. trump this, of course.

4) Confidence is all-important and should absolutely be the deciding factor in whether you chuck serviceable tires or not. You may be riding no faster than you are on the street and completely within the limits of the tire but if you're not confident then your enjoyment, ability to learn, and safety all are seriously degraded. It's really important to remove anything that makes you nervous. This is one reason why I run warmers, even though the instructors don't. I know intellectually that within a lap my tires will be sticky. I know intellectually that I don't need warmers. But that nagging doubt about having a cold-tire crash is simply gone if I use them. That gives me mental capital to use on riding.
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Old March 9th, 2018, 03:20 PM   #6
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If the tires have been out of the sunlight and away from ozone (not in a big city) since they were made, it's likely that they'll be perfectly fine for a lot longer than five years. If they've been outdoors in Los Angeles (high ozone), and where the sun gets to them, they could be pretty hard and oxidized by the five year mark.
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Old March 9th, 2018, 06:15 PM   #7
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If you have ANY concern the Dunlops might not be up to the job. Mount the new tires. The peace of mind alone is worth it.
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Old March 9th, 2018, 06:24 PM   #8
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If you're going to track, don't over do it. LEARN how tyres behave as you approach their limits. Old street tyres have a large margin-of-error at the limit. You'll feel them cause some lightness/vagueness in steering as they approach the limit. If you continue to push, they'll start sliding slightly. Push some more and they'll howl and really slide. You can get 50-100ft of sliding at full-throttle on old street tyres at say... 40-50mph on turn X.

Sticker DOT-R tyres have higher limit, but very little margin of error. They'll feel fine at 55mph on same turn-X, then at 56mph, you're flat on your ass with no warning.

Learn to feel for the limit of any tyre and you'll be fine. Personally, I think old street tyres are safer for beginners because they have lower limits and wider margin-of-error.
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Old March 9th, 2018, 08:09 PM   #9
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Quote:
Originally Posted by DannoXYZ View Post
If you're going to track, don't over do it. LEARN how tyres behave as you approach their limits. Old street tyres have a large margin-of-error at the limit. You'll feel them cause some lightness/vagueness in steering as they approach the limit. If you continue to push, they'll start sliding slightly. Push some more and they'll howl and really slide. You can get 50-100ft of sliding at full-throttle on old street tyres at say... 40-50mph on turn X.

Sticker DOT-R tyres have higher limit, but very little margin of error. They'll feel fine at 55mph on same turn-X, then at 56mph, you're flat on your ass with no warning.

Learn to feel for the limit of any tyre and you'll be fine. Personally, I think old street tyres are safer for beginners because they have lower limits and wider margin-of-error.
I totally disagree.

Old tires slide quicker, but are not necessarily more predictable than a newer/stickier tire. An old tire is going to lock quicker during hard braking than a newer/stickier tire - and that's not an advantage or safer.

Tires have different characteristics at the limit, but I don't think you can say absolutely that an old tire is more predictable.

You could easily lose the front, and go down, with an old tire where you would have been totally fine with a new tire with more traction.
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Old March 9th, 2018, 10:04 PM   #10
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Originally Posted by jkv45 View Post
I totally disagree.

Old tires slide quicker, but are not necessarily more predictable than a newer/stickier tire. An old tire i going to lock quicker during hard braking than a newer/stickier tire - and that's not an advantage or safer.

Tires have different characteristics at the limit, but I don't think you can say absolutely that an old tire is more predictable.

You could easily lose the front, and go down, with an old tire where you would have been totally fine with a new tire with more traction.
Compare the bell-curve groupings of these tyre. Sure there may be outlier examples that don't fit the curves, but most will fit. And predictability is matter of experience and practice. I can say you shouldn't go outside when it's raining because you might get hit by lightning. But if you combine large sampling sizes of lot s of people in lots of storms, there's pattern that will develop and any one individual can expect to fit in bell curve.

I used 8 different sets of tyres at 48 trackdays last year on two wildly different bikes; 30-bhp 250R and 120-bhp CBR600RR. Tyre ranged from 8-yr old BT-45s to super sticky Alpha 13-SP that you can't even buy. I'd swap wheels between sessions for back-to-back comparisons. They all fit those general characteristics; old street tyres slid sooner at slower speeds and were easier to control at the limits, can even bring back after sliding.

The stickier tyres had great grip with higher limits, but were much more difficult to control. I had to approach their limits much slower, maybe just +1-2% faster each lap. Going over their limits was much more unpredictable than street tyres; sometimes they'd chirp before sliding, most times not. Bringing them back was much more difficult due to limited warning. In fact, the two times I crashed last year were on sticky tyres 1 on Dunlop and 1 on Pirelli, both with no sounds or sliding. Just fine one moment and the next I was on ground.

I consulted with my friend & coach who raced TZ250s professionally in AMA back in '90s. He said yep, that's how sticky tyres work. The higher the limit of grip, the more knife-edged the behavior. Like starting out racing on small bikes teaches you finesse and cornering speed, starting on street tyres teaches you how to feel for the limits of adhesion. Knowing when you're getting close and balancing steering & throttle to not go over.

After my 2nd crash, he suggested i go back to street tyres. I gradually improved my speeds and times well beyond what I was able to previously do with race tyres. I could hold throttle on for more time on track, all the way through turns with both tyres sliding. After learning how to find limits of street tyres, moving up to stickier tyres was easier this time because I had learned how to feel for limits and how to control them at their limits. Things happen a lot faster with sticky tyres and require much faster reflexes and response.

If you lose front-end on street tyre, you didn't catch HUGE warning signals. If you had been on stickier tyres, you most certainly 100% will have crashed as well in identical situation because the signals are way, way smaller and much more subtle.

Last futzed with by DannoXYZ; March 10th, 2018 at 10:18 AM.
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Old March 10th, 2018, 02:05 PM   #11
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I guess I would respond to that by asking what gives a new rider a higher level of safety on the track, especially given the pace is moderate?

A set of old tires that are close to breaking traction frequently or a new set of tires that are significantly farther from their limit?

I've ridden on old tires that slide easily and fresh tires that slide when pushed hard, and can't say that the older tires gave a better warning.

Back in the day, most sticky tires would give up quickly when pushed to the edge. I don't believe that is the same with today's technology.

As far as stopping goes, no way is an old tire going to give you the same performance as a new one.

I guess the OP can decide for himself which one of us is right.
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Old March 10th, 2018, 03:14 PM   #12
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Does someone have to be right? Different riders have had different experiences, that should be OK.
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Old March 10th, 2018, 03:17 PM   #13
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It's sounds like you've haven't taken many tyres to the limit since your technique appears to be lacking feel and feedback correction:

1. Drive down straight at 50mph
2. Slam on brakes down to 40mph
3. Crank over steering at 45-degrees

Then apply the same operation to any and all tyres. In which case, yes a tyre that has 39mph limit would slide while one with 41mph limit would still grip. However, that's not how riders brake and determine limits of their tyres.

Most riders are taught to roll on the brakes gradually and feel the tyre. When it starts to feel vague and maybe even squeal, back off slightly to be just below limit. That's the braking technique that gets you maximum performance from any tyre. Note that this technique is completely speed-independent. It works in the dry, it works in the rain, it works in the snow. It works regardless of type of tyre, street or race. Sensing feel and feedback and adjusting accordingly is vital rider skill.

Sticky track-oriented tyres do not give as much feedback as street tyres, millions of racers and trackday riders will tell you that. I'm just wondering where you got the data for your claims? How many days did you make it to the track last year? His many times did you lock up your tyres under braking and his many times did you slide your tyres under full-throttle around corners last year? Last 2-yrs? Last 10-yrs?

Braking has technique. If you grab a handful of brakes an lock up tyre, it's not the tyre's fault, you're well beyond limit of any tyre. The difference between old street tyres and sticky track tyres is only 5%, within atmospheric variations and rider's performance day-to-day. I've heard endless wannabe racers blame their tyres for their crashes, "cold tyres", " wrong pressure", "wrong compound", yadayada. Yet they had brand-new state-of-the-art tyres that pros use. Crash database from track day providers show that most crashes involve sticky DOT-R/race tyres.
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Old March 10th, 2018, 03:23 PM   #14
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Quote:
Originally Posted by DannoXYZ View Post
It's sounds like you've haven't taken many tyres to the limit since your technique appears to be lacking feel and feedback correction:

Braking has technique. If you grab a handful of brakes an lock up tyre, it's not the tyre's fault, you're well beyond limit of any tyre. The difference between old street tyres and sticky track tyres is only 5%, within atmospheric variations and rider's performance day-to-day.
You have no idea of my experience or skill level, so your observations are not valid - but thanks for the insults!

5%? Really? No.
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Old March 12th, 2018, 10:39 AM   #15
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my tire install has been delayed since I cannot fit my pit-bull front stand through the front without hitting the fairing. It looks like the front fairing needs to be removed to use a front stand? (the one that lifts the bike from the steering collumn)
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Old March 12th, 2018, 10:52 AM   #16
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Yeah, I had that crunching issue too. Look under and see where it touches the fairing? Trim a semi-circle opening for stand. Stands with rubber fingers supporting under fork-tips work also.
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Old March 12th, 2018, 05:50 PM   #17
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Originally Posted by DannoXYZ View Post
Yeah, I had that crunching issue too. Look under and see where it touches the fairing? Trim a semi-circle opening for stand. Stands with rubber fingers supporting under fork-tips work also.

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