Effects of Cold Tires?

[heisler3030]

Hey folks -

I had a crash a few weeks ago at Thill when I got over-eager on the first lap and lowsided in T3.

There were a number of factors at work but I think cold tires was the primary because I was very surprised to feel the rear wash out so quickly.

The story goes like this:

New tires (209GP Hard) and one session at medium intensity with no problems.

Second session I go out with A's and crash on lap 1 in T3. I thought I was taking it easy!

In retrospect I think I made the following mistakes:

- A's running faster than B+, so what seemed "not that fast" relative to other riders was faster than I thought

- Taking T3 too wide and riding on the off-camber section, as opposed to the flatter inside

- Not being smooth enough in my throttle roll-on in T3 (too abrupt)

- Not anticipating the reduced traction from the cold tires

I'm consciously working on all the above to prevent repeats, as well as picking up some tire warmers to avoid the cold-tires situation again. However it would be interesting to hear educated info about how different compounds respond in cold vs. hot conditions.

My theory, based on this experience, is that hard compound race tires have even LESS traction than street tires, when not at temperature.

Is that a true statement, or just my imagination? I mean, based on my recollection of the incident, it did not seem like I was pushing the limits, even of cold street tires! But then we know how memory can make these things more favorable.

Thoughts, flames welcomed!

-Hamish

 

[WDZ]

Hey folks -

I had a crash a few weeks ago at Thill when I got over-eager on the first lap and lowsided in T3.

There were a number of factors at work but I think cold tires was the primary because I was very surprised to feel the rear wash out so quickly.

The story goes like this:

New tires (209GP Hard) and one session at medium intensity with no problems.

Second session I go out with A's and crash on lap 1 in T3. I thought I was taking it easy!

In retrospect I think I made the following mistakes:

- A's running faster than B+, so what seemed "not that fast" relative to other riders was faster than I thought

- Taking T3 too wide and riding on the off-camber section, as opposed to the flatter inside

- Not being smooth enough in my throttle roll-on in T3 (too abrupt)

- Not anticipating the reduced traction from the cold tires

I'm consciously working on all the above to prevent repeats, as well as picking up some tire warmers to avoid the cold-tires situation again. However it would be interesting to hear educated info about how different compounds respond in cold vs. hot conditions.

My theory, based on this experience, is that hard compound race tires have even LESS traction than street tires, when not at temperature.

Is that a true statement, or just my imagination? I mean, based on my recollection of the incident, it did not seem like I was pushing the limits, even of cold street tires! But then we know how memory can make these things more favorable.

Thoughts, flames welcomed!

-Hamish

I think that your assesment is spot on. You are better than most people when it comes to realizing what went wrong. I can't provide you with any better info than what you have already posted.

I believe a race compund would be more prone to slipping than a street tire when cold because street tires are made to heat up quicker and easier because most people in their right mind will not ride on the street like they ride on the track. I am no professional thats for sure just giving you my 02cents.

 

[Holeshot]

Hammish, a few things:

How did the crash take place and what did the bike do in T3? Were you late turning in and adding lean angle as you continued forward progress?

T3 is a turn you do not want to rush, by any stretch of the imagination. I crashed there in a practice a few years back by backshifting the bike and getting way too far into the off camber section.

Did the front or rear of your bike lose traction? How hard were you on the brakes, how much lean angle were you carrying, were you on entry, mid corner? What was the weather temp out?

Those questions really help parse down to what the exact cause is. It could be a factor of being too far off line on a hard tire on a cold track...and maybe the tires weren't too cold....

 

[J-Boat]

Another factor is that turn 3 is the first rightie...

 

[heisler3030]

How did the crash take place and what did the bike do in T3? Were you late turning in and adding lean angle as you continued forward progress? ...Did the front or rear of your bike lose traction? How hard were you on the brakes, how much lean angle were you carrying, were you on entry, mid corner? What was the weather temp out?

IIRC the crash happened as I was rolling on to the gas near the apex of my corner. It was a rear-wheel low-sider. I was not on the "racing line" as it was first lap and there was some traffic to the inside. I went further outside than I would have usually and definitely was on the off-camber section. This is not the first time I have ventured into that territory and I didn't *feel* I was running anywhere close to the speeds where it would be a factor.

I was not on the brakes at all. I'm usually pretty good on lean angle and I know it wasn't a case of mid-turn adjustments, but the off-camber section aggravates the angle and was definitely a factor. I'm not sure that was the primary one though.

I've basically convinced myself it was cold tires because it just felt like such a surprise when it happened. I've probably run that line 50% faster before with no problems

I have since changed the way I run that corner, beginning my turn at the 1 marker so that by the time I get to the off camber section I am basically already turned and on the gas. This has definitely helped with the pucker factor I have encountered since the crash, and is faster, I think, as well. I'm rolling on the throttle in a much safer section now.

 

[kiltwearinfool]

It could be a factor of being too far off line on a hard tire on a cold track...and maybe the tires weren't too cold....

Isn't it more difficult to get a hard tire up to temp in cold conditions vs a softer tire in same conditions? I'm also wondering if the track would be warmer after lunch than before, because of more time in the sun...

Personally I've noticed a big difference between tires that have been brought to temp in warmers vs. just having the warmer on them in between sessions. Granted, I'm thinking of an experience from a wet trackday and softer DOT tires (208GPs), but I still think there's enough heat lost during a lunch break to effect grip. But I'm old, slow, and opinionated. Take that into account, too.

 

[heisler3030]

Yeah, hard tires is something that definitely aggravates the problem. The weather was not warm but neither was it exceptionally cold - probably in the 60s.

Curious about your comment on tire warmers - are you saying you notice a difference between tires heated "on the track" and those heated in warmers, or something else entirely?

 

[kiltwearinfool]

Only that tires that have been brought up to temperature with warmers give me more confidence than taking it easy for a few laps, hoping I've got enough heat in them.
I don't have the attitude that warmers give me a license to tear it up from the first turn, but I feel more confident in the grip available when I first head out to a session.
I also wrap the tires in between sessions, (and turn them on about 15-20 minutes before the next session, depending on the ambient temp) to keep the heat in the tires.
That said, Holeshot will tell you I'm a recreational trackday rider, I have no idea what I'm talking about, and he can stay in front of me riding one-handed :laughing

 

[Holeshot]

They should come up to temp about the same John, to answer your question. The heat range may be wrong for the current conditions and allow possible cold tearing (as michelins have done on me), but that also could be an effect of air pressure as well.

Sound like you mostly have it figured out. That low line often leads to losing the rear end as you did and not the front due to the weighting of the bike. You've got it figured correctly that there is no true "low line" in T3 and the lower you get while adding lean angle, the worse it gets. If you get in that turn too hot, it's a mistake to try and just keep cranking it over while trying to scrub off speed many times. IMO of course.

 

[elskipador]

I had a crash a few weeks ago at Thill when I got over-eager on the first lap and lowsided in T3.

New tires (209GP Hard) and one session at medium intensity with no problems.

i'm thinking the biggest problem a couple of weeks ago @ t-hill would be temp.... was the high even 70? either way a +2 rear is not the right compound for that track @ that time of year. you should have been running a 3136 (med) or a 3166 (soft).

 

[com3]

personally...and most people think i'm an asshole because of this... i don't believe in "cold tires made me crash." it's not the tire's fault that you over extened yourself.

sure, they don't grip as well when they're cold...that's why you ride accordingly. :thumbup

anyhow, glad you're not really hurt.