froggy47

I have been wondering for some time & got to posting this question.

During the race season, say May - November, we all know that soft compounds like 710/a6 out perform high performance summer tires for a variety of reasons only one of which is "rubber" compound.

And the high performance summer tires out perform all season tires, and so on.

But if you get to run in "winter" lower ambients, is the rule still the same, or does the a6/710 lose out because it can't get into the rubber temp that it works best at?

The reason I ask is that if I occasionally street drive on a6/710 and the ambients are say 50 degrees and I am getting no heat in the tires (because they are going normal speeds on the street, they are really really low grip, seems like much worse than, for example, Sumi's or F1SC.

Discuss.

talon95

I think unless it's very cold (sub 40 degrees), R comps will still be faster if you work to build/keep heat in them. 710's are a bit better at low temps than A6's, so I'd probably choose those if I were buying just for those conditions.

I'm also assuming we're talking autox. If so, this also depends on how many runs you make. If you're only doing 3, then it might be tough to get enough heat, but if you're doing 4+ then the last run or 2 will definitely be faster if you're managing heat (tire covers, fence, riding brakes to/from the course, etc...).

Dave G.

L98Terror

I ran Lime Rock a few years back we woke up to frost covered cars, track temps were probably 30-40 degrees and the air was 20s in the AM maybe mid 30s in the afternoon. I still was able to run sub one minute lap times in a stock C5Z with old Hoosier A0S05s (or whatever they were called). You can get some heat in those puppies and it's a lot harder to over heat a A in cold temps.

R compound tires are almost always faster ever in the wet

sperkins

It's definately not a good idea to run A6's or the like on the street for many reasons - especially when it's really cold.
I seriously doubt you'd be able to get enough temp into them to gain enough grip to be safe.
Ever gone out on a hot track with near frozen R comps?

froggy47

That's mostly what I am wondering about, street driving on r comp's when it's cold. It seems when they have heat (impossible at street speeds) they are fine but when they are like 30 to 60 degrees they are worse than street tires.

I thought it might be a characteristic of the rubber grip vs. temp where the grip falls off MORE than the street tire.

Just wondering. I don't know anything about the "chemistry" of tire compounds but I know there are temp characteristics.

CorvetteZ51Racer

Before driving A6s or R6s on the street again, you may want to go check out Hoosier's website where they explicitly state do NOT drive them on the street. DOT compliance has a lot more to do with tread depth than construction, and Hoosier DOT R compound tires have a very light construction to make them fast for racing, which translates to NOT durable for street driving. I'm not talking about the rubber compound, but the carcass strength and design.

froggy47

I am well aware of all that, actually, but thanks. I started the thread to explore the chemistry of the rubber vs. temps, rather than "Should I do this or not".

I have "heard" that race rubber is "overly" sensitive to cold and that if you, say, took an a6 to 10 deg f and then thawed it out it could be permanently damaged, where OTOH an all season tire would be unaffected.

True or fiction?

bobmoore2

I've heard that also. In fact I think I've read a warning from Hoosier or Kumho that you should never let them get to freezing temperatures.

bobmoore2

There is a certain low temperature where you can never get enough heat into the tires. Any heat created by rolling resistance or turning/braking friction, will be sucked out of the tires into the cold pavement and cold air. It's somewhere in the low to mid 40s, I think.

L98Terror

I kryo treated all my tires last year, the real queation is what temp do the tires actually freeze?

davidfarmer

My definition of "freezing" is solidified, so tires are already "frozen". I do know many tires will crack severely if exposed to sub-water-freezing temperatures for long (storage in a trailer for instance), so you should be careful.

I've found that R tires are fine on the street during warm weather, but even in cool fall/spring weather, they chatter and are very unpredictable. They are also much less predictable at the track in cold weather, but ultimate grip is still higher than street tires that I've run.

I think we had an identical thread a few months ago btw.

Aardwolf

My daily driver would not start the other day, so I used the 'vette to take my daughter to school. It has v710's and they were fine, even in the snow. It was about 10° outside for temp. They aren't A6's but I thought the input may help. I was surprised how well they did on my snow covered road.

froggy47

That is what I am getting, chatter & I can just loop the car on the crown of the road if I want to. It seems that the a6/710 rubber just goes from soft/grippy to very hard (like a high mileage tire) and zero grip, just by the cold ambient temp.

If you have a link to the other thread (I can't find it) I'd like to read it.

redtopz

I was at the track yesterday on some old A6 tires. The weather was 34 - 38 F and foggy/damp. Only 5 other cars/drivers were dumb enough to be there with me . Anyway, the A6's still had way more grip than street tires, although I had to be cautious and drive smooth. Even that didn't always work as you can see at the end of my vid.