Tire Compounds

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G.B.
Posts: 54
Joined: February 17th, 2008, 10:59 pm

Tire Compounds

Post by G.B. »

I note that Hoosier produce FV tires in two compounds: R45B and R55A.

How many heat cycles should be expected from each type of compound?

Is there a dramatic difference in performance between the compounds?

Thanks
GB.
maurus97

Re: Tire Compounds

Post by maurus97 »

I've heard varying accounts but I'll give you my take based on personal experience. First off the 45 is a softer compund than the 55 which makes it good in cold weather.
In 2007, I ran my first national April 26-27 at Gateway(st louis) and used the 45's for the first time. The weather was in the high 40's to low 50's. I liked the way the car felt on the tires. However, Gateway is a shorter track that doesnt seem to incorperate many G's or put much stress on tires. I failed to take this into account heading to the next national. The following weekend at Blackhawk farms, (another shorter track) I used the 45's again. To put it bluntly: They were TERRIBLE right out of the gate. I thought they would be great due to the fact that the weather was the same as the previous weekend(40's & 50's) but the car was loose as hell, tight as hell and everything in between. Every corner I was fighting the tires. Now there are a few things that must be taken into account here. 1) It was the second weekend on the tires which might or might not say something for the longevity of the 45's. 2) Blackhawk puts more stress on tires than Gateway does.
I was told after that crumby session at blackhawk by someone who really knows their stuff that the weather was too warm for the 45 compound and that they do indeed not last as long. How long they last I don't know but like I said, they were fine one weekend and bad the next, wether that was due to air temp. or longevity or both who knows?
My educated guess would state that the 45's are good in cold weather but don't have quite the life span of the 55's.
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Tire Compounds

Post by brian »

We've used the 45's well into the 80's with no apparent problems. The 55's seem more durable but take a bit longer to warm up. We're getting well over 5 cycles with no appreciable loss of grip. As a matter of fact, I prefer the tire after a couple of sessions. I have experienced a unexplained change in grip, like Nick mentioned, but usually caused by going to new tires. As I said, the Hoosiers are better after broken in.

One thing to consider is track surface. If your track of choice is well seasoned it might be easier on tires and need the 4 5"s. If the track does not have enough straightaways, the tires won't get cooled and the 55's may be in order.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
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