In that vain, do you think the 225/45 would work better on a 10" wheel?

 

Well the reality is 205 SM6s (8" tread width) are actually more like a 225 (~8" tread width), I don't think Sav's statement is nearly as applicable as the "205 on 8, 225 on 9" statement.

a 205 is usually closer to lower 7.x".

 

Hoosier R6 was about 3 seconds faster on a 2 mile course than the Star Specs. Same car, same day but in a HPDE format. In a race the R6 might be even faster.

 

I think the 225/45 R6 on a 10 would see a similar advantage to a normal 205/50 on a 9. Small gain, but small enough that it's difficult to measure.

 

The what tire is faster question depends on many variables. Back in 2004 we were running the 12hr at VIR in an SM and they had an open tire rule for that event. The RA1 is the tire we had run usually as it was the spec tire. We had also run this race the 2 previous years with the Data Aq running so we knew what to expect. We figured open tire rule, we'll get Goodyear GSCS tires as there "faster" and we'll kick butt. We go down and on the test day we try them out. First guy goes out and is 3 seconds off the pace. He comes in and says how the car is on rails thru the corners. I go out next and same results. I'm 3 seconds off the pace. And the car was on rails with those tires. We put on an old set of RA1's and I go back out and after 2 laps I'm back on pace. We go back and compare data between the years and it turns out were losing about 5mph on the straights as the tires stick to well. Think getting your hand off a piece of flypaper. Stickier tires use more HP to move. In a large HP car, probably not a real problem anywhere. On anything under 250HP you need to weigh how much time you gain and lose on the straights and corners based tire grip and the track your on. So whats faster usually does not equate to whats the stickiest tire. FYI
Chris

 

ugghhhh that was hard to read

 

I always wondered why I never heard of Conti slicks at all outside of the CTSCC. Are you going to be driving for them next year? I didn't make it to Indy this year but last year I enjoyed it, some right hand turns to keep me awake during the NASCAR weekend.

 

Yeah, of course things are going to be in relation to each other and it's a vague guide with understanding that it isn't The Law That Will Never Change or Be Challenged Never Ever. For comparison's sake, the Racelands can be faster than Xidas... with the stipulation that there's a hotshoe driving the car with the Racelands and a DE1 student driving the car with Xidas.

 

The Conti slicks are made by Hoosier. They are basically a slick version of the old R3 tire, with some modified rubber formulation (as far as I understand).

The Grand AM series used to run spec Hoosier tires. Then Continental paid a bunch of money to be the "Tire Supplier / Title Sponsor", and then they paid Hooiser to continue making the tires and start painting Continental on the side of them.

The reason you haven't heard of them outside of CTSCC is that they are only sold to CTSCC teams, and no one in their right mind would pay the exhorbitant price for sh*tty tire unless they are required to by rule.

AND, unfortunately NO, I am not slated to do any Grand AM races this year. I'm taking some time off as I recently had my second child and the time commitment to do Grand AM was eating up all my family time.

 

There is no comparison there. I was talking about, with all other things being equal, the difference in a car's performance with different tires. You were using human performance and suspension performance combined. Sorry, not a good example.
Chris

 

I wasn't clear what I was challenging in your example, the claim that stickier tires might not be faster because the Miata has a HP deficit. I agree with what you said; however, your experience in Spec Miata is fairly specific and you don't necessarily need 250hp to run some of these tires.

Sorry for the confusion.

 

Fixed

GRM just did an article on this, lots of math and stuff, but they basically agreed with you.

They also did a comparison on summer tires, I'll try to find it.

 

Can anyone comment where the maxxis rc1 falls into this? I'm thinking it's similar to the NT-01 maybe -.5?

 

lol just seconds after I posted I find this. https://www.miataturbo.net/wheels-ti...8/#post1087024

 

I would like to read that article if you have a name...

 

I have been running the 225 NT01 on 10"s all year. While I can't give you time comparisons vs the 9" wheel I can tell you they do feel great on a 10". The decision to run the 225 on a 10" was one of necessity.

 

Varies depending on the car and weather. At worst, they're equal. Cooler weather and/or heavier car, the RC-1's are faster. On our light Miatas, we need to have track temps under about 90* for the RC-1's to really out pace the NT01's. The RC-1's do last longer and steer better. That's saying a lot because the NT01's steer well for a hard compound HPDE level tire.

None of the Socal Miata HPDE crew but NT01's any longer.

The chart looks pretty accurate to me except I would put the Rivals and RS-3's on the same line. The Rivals are just easier to drive and last longer. Setup can be off a bit and still be fast with Rivals. RS-3's require a closer to optimum setup for the car to feel good. This is largely because you can bulldog a poorly setup car on Rivals into rotating without scrubbing too much speed. Exact same input/entry speed with RS-3's on the same car and you're farming.

 

Where does the RA1 fit into all of this?

 

Great info in here for a track noob like myself...


Any more info on heat cycling would be good as well- specifically how long they last or when they start to fall off would be helpful to know. Maybe included in the first post alongside the time differential?

 

Slower than Rivals. If you're still running RA1s and you aren't required to by your ruleset or budget, you need to evaluate your life choices