AudiOn19s

Frank, seems like each tire is a little different. Might have to look for first hand experience with someone with the same tires.

FWIW I ran a school last year when it was freezing and I ran Bridgestone S03's in the morning and Toyo RA-1's in the afternoon and the Toyo's were fine and had LOADS more grip than the S03's. High temp that day was in the 30's. However buddy of mine running MPSC's packed up and left because he couldn't get any grip out of his tires at all.

You doing BMW club this weekend of PCA next?...I'm done for the year, car is detailed and prepped for winter now.

lawjdc

My experience has been similar. MPSC's are worthless below 40 degrees, no matter how long you try to warm them up. Toyos, meaning RA1's and now R888's, are surprisingly good below 40 degrees, but obviously are much better at higher temperatures.

Patrick E

Wasn't there a pretty specific warning issued by Toyo (and maybe one other manufacturer?) regarding safe operating temperatures for R-comps? I remember seeing copies of it last year when I did a December event at VIR. IIRC, it warned of sidewall cracks developing when tires were exposed to temps less than 35 degrees.

38D

Then your buddies are not good. Don't mistake someone's lack of ability as a tire issue.


This is just not true. Yes the limit is not as high when it is cold, but the tire still sticks fine. They are no harder to warmup than any other tire either.

RonCT

Well, we're talking about well seasoned Black / Red run group of CVR (largest PCA chapter), which is loaded with some quick club racers.

When it's pouring rain, what do you think is faster -- PS2 or Hoosier R6? Same applies when it's 28 degrees and the guys with Hoosiers and Cups are either sitting it out waiting for some heat or are out there taking it "easy" because they don't want to spin and crash while driving on hockey pucks.

RE warnings - I have read warnings about R-comp being brittle when cold.

38D

I'm from CVR. Most black and most red run group drivers do not drive fast enough to get a MPSC hot, even good conditions. That goes for nearly all regions, not just CVR. The ones that do would not have problem running them in cold temps.


Standing water or just a completely/really wet track? On a really wet track, Hoosier are actually very good. When I ran them at the 2006 WG race, I was shocked at how good they were in the rain. In outright standing water, they suck.


The number of heat cycles greatly impacts how these tires behave in the cold. Only a few heat cycles and its fine. Try to run an R with 40 heat cycles in the cold...doesn't matter Hoosier or MPSC, it will suck. Slicks are even more brutal in the cold when they have a bunch of heat cycles. But a sticker slick in the cold is amazing. Maybe your buddies are just running old tires.

Bryan Watts

Sounds like the issue is that street tires make about the same grip whether it's 80 degrees or 40 degrees because they are so hard. R-comps make MORE grip on a hot track than they do on a cold track, but even on a cold track they make MORE grip than a street tire because they are softer rubber...I think the delta between the grip they make on a cold day and the grip they could make on a warmer day may be what causes people to think they aren't making any grip when cold.

That's not a compound issue...that's a tread issue. Cut some tread into the R6's so they can move water and they will be 10+ seconds a lap faster than street tires. Even better if you can use the Hoosier rains made out of the softer A6 compound.

Do you have any data to back that up? I have a hard time believing that a street tire is softer according to a durometer than a R-comp at any temp we would see at the track. We keep a tire durometer in the trailer...perhaps I should do some testing around the paddock this winter?

Bryan Watts

That doesn't have to do with the tread...it has to do with the sidewalls that are made of harder rubber so that they can be stiffer. You definitely need to be careful with the sidewalls of race tires in the cold, but as long as you have them aired up properly, it's not a big issue. The problems come when unmounted tires are dropped during shipping, at the shop, etc during cold temps and the hard, brittle sidewalls can crack.

Bryan Watts

Exactly...heat cycles become a much bigger deal the softer the rubber.

Bull

I carry a durometer and will also do some testing the next time I am at LRP, etc. in cold weather.

Ah, tire myths....

fhp911

My experience with MPSC is that they run fine even in cold Fall weather at WGI and LRP provided that you let them warm up before pushing on them. It is truly astonishing how poorly they grip (and brake) for the first lap or 2, and also how profound the change is once they get some heat into them.

I have never run on my PS2 because it's been 'too cold' for the MPSC.

RonCT

Here's the Toyo advisory on R-compound tire use / storage in cold weather. Looks inadvisable - the "soft" compound appears to get brittle and crack. I also read a post by a Miata racer that ran in the cold and he couldn't get more than 130 degrees into his R-comps.

I guess what I'm trying to say is if it's below freezing (ie: my 26 - 28 degree example), then stick with streets like the PS2. If it's a balmy 40 degrees, R-comps. As others have said, if it's warm enough for R-comps to work and you give them enough laps to try to get the heat in them, they should be fine. But you have to wonder just how much heat you can get into a tire when it's 32 degrees and the track surface never gets any warmer.

bobt993

As Colin pointed out. Slicks are good in the rain, wet, just not in standing water. Same with MPSCs in the cold ifffff you get heat into them. Here are 3 vids of all examples. Slicks in full wet 60degs, other racers did not get heat in the tires during the warm up. Slicks in the cold wet 36 to 40degs race at VIR, I had R6 wets on with little tread left. MPSCs in 40deg during a DE at SP last year track is still wet.

http://bobt993.neptune.com?selectedalbum=bobt993368020

http://bobt993.neptune.com?selectedalbum=bobt993355692

http://bobt993.neptune.com?selectedalbum=bobt993341732

todinlaw

Wimp-- I am doing PCA next weekend. Get that queen out of the moth ***** and join me.

todinlaw

thanks for all the input. I think what I am going to do is start out with the Rcomps. they have a bunch of Heat cycles so i don't care if it damages them because this is the last session of the year. I will bring the PS'2 also and if the R comps are unmanageable I will switch to the PS'2 and see if they are any better. So I guess the answer may be both. My last DE two weeks ago the first session we had a 40 degree start. going down the back stretch at Mid-Ohio they felt like rocks the first 3 laps. Like the tires were not rolling round. I taped up the brake ducts and once i got the rotors warm and the tires warm the came around. but it will be colder this time maybe by 10 degrees or more. I will say until I got a little heat in the tire it was as good as winter driving. Good thing I grew up in the snow belt.