Tire Talk

[sdcat]

I had a very nice time out with the VARA group this weekend. They are a friendly and pleasant group, and have been extremely welcoming, even though I am the only one there that doesn't have a true vintage car. They said to invite any other sevens around to join them. They would be happy to have other "continuation cars," referring to cars like ours which share enough aspects of the original vintage cars to be similar in looks and intent. I plan on continuing to run with them.

I have a bit of a tire obsession, and wanted to share my latest tire reviews. This past weekend I had a set of the Avon ZZR's in the A60 compound, and a new set with the A24 compound. I also had some old Avon A11 compound bias slicks. All were similar size. I run 8" rear, 7" front these days. We ran the 25 CCW configuration, so I don't have any times to compare it to from previous runs. It deletes the Bus Stop, but adds the Star Mazda turn. My best time of the day was a 1:55.

I switched back and forth between tires over the weekend, and was very impressed with the ZZR A24 compound. I ran similar times as the Avon slicks. The slicks had about 8 days on them, and the ZZR's were new, but my impression is that the ZZR is within a few seconds of what the slicks would be new. Of course, my setup was not ideal for the slicks, since I run too much camber. Yes, I know.

The ZZR in A24 compound vs the same tire in A60 compound is night and day. The A60 ZZR's were a year old, but I can confidently say that they weren't even close in grip when new. I've used the A60 compound (which is what Caterham sells) enough to say that it is roughly the same grip as a typical hard compound DOT R like the Toyo RA-1 or RR, and not nearly the same grip as a Hoosier A6 or Kumho V710. The A24 felt faster than any of these. And it never went off, even after hard driving in summer temperatures.

The A24 ZZR feels almost as grippy as a slick, and I had lap times that were comparable to the well-used slick. If it holds up, I think this is by far the best deal in a track tire for our cars right now. It will be a bit slower than a slick, but heads above the other DOT R offerings. I got mine from Roger Kraus.

The ZZR A24 part numbers and sizes are :

185/55R13 part number 13982
215/55R13 part number 13983

Thanks for indulging,

Justin

[magnusfeuer]

Justin,

Where did you purchase your A24 variant of the tires?

/Magnus F.

[sdcat]

I bought them through Roger Kraus Racing. He only gets shipments every few months, so might not always have them. I think he said some new ones are coming this month.

Glad to see you are getting out in the car!

Justin

[Sean]

Current pricing of ZZR at RKR shows $864 for 2x 215s (19.0 lbs. each) and 2x 185s (15.85 lbs. each).

Current pricing of R888 at RKR shows $672 for 2x 205s (19 lbs. each) and 2x 185s (17 lbs. each).

(I'm sure the final prices of both above will ultimately be higher, after taxes, old tire disposal, mounting, balancing, etc.)
The Toyos seem to last a very long time with little reduction in grip. At a price difference of $190, I am tempted to try the ZZR, but fear they won't remain grippy as long as the R888s, which seem to defy all logic in their ability to remain grippy for long periods of time and use - my current R888s are three years old of primarily road use now, and Murphy has been track-whipping his for at least that long. Hmmm... Damn you, Justin! (he said, light-heartedly)

[magnusfeuer]

I ran my R888 (unknown compound) on the PIR track before my ECU burst into flames, and I was a little disappointed in grip in comparison with the V710 that felt like my face wanted to continue straight ahead as I entered a corner.

Once I have my car back I'll bring both sets to track to do a side-by-side comparison.

Given my new location, I also need to look at rain tires and some kind of weather solution that fits over my roll cage.

/Magnus F.

[slomove]

........I also need to look at rain tires and some kind of weather solution that fits over my roll cage....

Helmet?
The tech guys may object to some cloth cover on the cage.

I did one track day in heavy rain many years ago at Infineon (or whatever it is called today). The rain was the smallest problem. You just get wet and while on the grid I used an umbrella (no umbrella girl, though).
But shoveling a bucket of mud out of the cockpit after an unintentional excursion was not much fun.

For that matter, I noticed the disadvantage of the Quaiffe LSD under such conditions. Once a rear wheel looses traction due to mud on the pavement, the other wheel gets double torque plus twice the lateral force which is not that great when it is at the limit on wet surface already.