I didn’t even consider the lower wear and tear with a 200tw tire, longer hub and brake life, #winning!
I didn’t even consider the lower wear and tear with a 200tw tire, longer hub and brake life, #winning!
Truth! We'll see how different the laptimes really areOriginally Posted by mach1
Daniel Records
CMC # 34
Tire test setup:
It’s important that if we do a tire test, we pay special attention to a wide variety of parameters to make sure the full package is suitable. We don’t need a different tire, we need a better tire. We also need to agree on the definition of “better” in this context.
First, per the rules, if a race car isn’t on Toyo tires, it isn’t “racing” in CMC (or AI). Without Toyo’s, no CMC season points are accrued, no Toyo bucks are earned. Also, if a legal CMC car is fighting for position with a non-legal CMC car, technically that could be considered out of class racing.
There are a couple of different ways to run this. If you have a non-legal car, you can “fun run” in your normal class. I think a better option is for the tire test folks to run AIX. That keeps things a bit separate and the “winner” of the tire test potentially gets a plastic trophy, some winner stickers, and a season championship! I’m happy to supply AIX stickers to any tire testers for this test. When we had both CMC and CMC2 racing together, I pushed for decals on the windshield and back glass so competitors could easily tell who they were racing for position with and who they weren’t. I think something like that would be good for this.
As I posted earlier, there are a number of relevant parameters we would be testing for. How does the tire feel, how well does it stand to abuse, if you overheat it does it come back after easing up for a lap or is it dead for the rest of the session, etc.??? These are pretty easy to test for in just a few sessions. In my opinion, we can only really tell what we want to about the tire under full race conditions with cars fighting for position.
The much bigger question is how much do the tires degrade with heat cycles? If all of the tire testers start and run the whole weekend on fresh tires, we learn exactly zero on this aspect. Ideally, this test needs to span multiple weekends and possibly multiple sets of tires. In order to figure anything out, we need to have a guy on stickers battling a guy who has at least one full weekend of abuse on his tires. We could have some testers start the weekend on fresh tires and have others wait until Sunday to put the stickers on. Josh is running a Houston DE the first weekend in March and could do his best to wear the test tires out before our race weekend. The more testers the better if we hope to get any real findings.
Getting useful data from a test like this is pretty tough. Initially, we have to figure out what these tires want and get them to work with our cars. What tire pressures do they want? Do they do better or worse with our camber settings? Do they work better with stiffer or softer sprung cars? Slapping on a different style of tire and judging them after a session or two without tuning is very useful. Also, some drivers adapt to changes quicker than others.
The other question is what specific data are we going to be looking at? Certainly lap times are key. Comparison of test tire lap times to Toyo tire lap times is certainly interesting but not really relevant to our test. We need to be looking to differences between tire test competitors. We need to pay special attention to lap time degradation between test subjects, especially those that are on tires with differing heat cycles.
One of the hardest parts of these types of tests is the other variables that are hard to control. Weather, traffic, car setups, etc. are all a big deal but not as significant as the difference between drivers. One example of things we can try to mitigate would be to have competitors swap tires between sessions. Have Josh start the race weekend on heat cycled tires while someone else starts on stickers. After a couple of sessions to set a baseline, have the two swap tires and see the relative change. This could help answer if the difference between cars is the driver or tire wear.
One other thing that would help with testing. The test drivers actually need to race each other. Starting on pole for the invert because you had a problem in the first race and trying to run away with it is something that I might want to do (OK, have done) but it isn’t helpful for our testing. Traffic, cautions, or other situations might lead to some of the test drivers having to wait up for the other testers.
On a personal preference note, I would prefer to suspend any tire testing for the Hallett event. The racing there is too much fun (sacred even) to split up the group. I’d love to see everyone on a fresh set of Toyo’s for this spectacular, multi-region event.
Richard P.
A couple of additional variables:
What is the tread depth of the test tire as it sits on the shelf and would they be faster if shaved? If indeed there is a compound/design that eliminates drop off due to heat cycles (or Richard's time at heat) then would the tire actually get faster and faster as the weight is shaved off and ultimately being fastest right before it cords? Is it possible we flip to a "thin to win" world where you're buying new tires every weekend, shaving them to 1/32" and hoping to not cord them before the checker?
Why the Azenis? There are at least 10 200utqg rated tires in 255 (which we ran for years) and some are a lot cheaper than the 615+. The Kumho V720 is 140!
Al Fernandez
So ok, taking my competitor hat off and putting on my series official hat...
Cars that are not cmc legal can’t score cmc points, so classing cars in six would appear logical. What Will does with such a run group would be his call. I have told Shawn Meze (nasa national competition director) about this discussion so hopefully atwe will get some input from nasa on the situation.
Al Fernandez
People talk about the R888 debacle. What went wrong there? 615's vs R888 vs R888r? Prices are about the same on Tirerack. Curious to know why everyone dislikes the R888?
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-Dylan
3rd Gen CMC Wannabee
The R888 when we were running it got greasy if you pushed it too hard. It wasn't fun to drive or race. It was said that it needed a more sophisticated driver to extract it's full performance. The AI/CMC group gave a big middle finger to that...
I would guess the compound has been revised since then, especially in the newer R888R???
Richard P.
The azenis have at least some pedigree in other race/track classes. See TT street tire class, and spec Corvette, without shaving (so far).
- Josh
CMC #50
Because this is a science experiment at this point, have you guys considered super sizing and running the 615 in TT or PTX/STX and Toyos in CMC in the same weekend to preserve car counts?
On a side note, will 225 tires fit my Z06 wheels? The desired end state here is reduction in costs, sure would suck if I had to run out and find new wheels.
Last edited by Supercharged111; 02-16-2019 at 02:18 PM.
RM CMC Director
Great point on sizing! A 245 is 150 per tire, same od and will fit 17x9.5 without issue, perfect tire!
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