I doubt AWD will get any more than 265's. I've got some ideas on a setup to make 265's work.

 

Glad I'm out of this rat race, same as luster, just slower....

I ran 255s and 245s back to back on my '04 STU EVO, once on concrete and again on a sealed lot.... I'll take the 245s all day long, on a 9.5" wide wheel the contact patch really wasn't much different, definitely not the 10mm you'd expect from looking at it on paper.. the taller tire means more lag on an already laggy setup (STU EVO)out of any low-mid speed turn. To each their own.

And understand certain drivers are not a "slouch"... others have integrity, I am definitely the latter, evidently a dying breed.

 

For what it's worth, as a point of reference for everyone else, you will not find a representative "sweeper" at Devens no matter what the course configuration, and you'll definitely not have two back-to-back ones.

 

Is there a such thing as a 255/35/17? 255/30/17?? Not that it matters because i have an X. But i think you'll find, contrary to your belief, that 10mm extra contact patch WILL in fact make a difference. Sure, you'll have to relearn your setup, but i think your subjective test using your butt dyno doesn't reflect reality. Datalog some stuff on a skidpad, then i'll trust your butt dyno.

But let's pretend 255's will give you decreased performance. It'll be more of an even playing field compared to the X's that have to lug around an extra 300 lbs of mass!

 

there's very real credit to wider not always being better for street tires. what i've seen is while rcomps pretty much don't care what size wheels they're on, street tires are largely impacted based on the width of the wheel itself. it's like the wheel width determines the majority of the contact patch, and the tire width just determines what part of the tire is touching the ground.

 

I do not believe that is true about street tires - or at least not the complete truth! From where I stand, everything comes down to whether you can bring given tire to the operating temperature. For some light cars (like Miatas for example) it is not easy to heat up successfully 225s, while 205 have no issues with that. For them, you can say that 225 will be slower than 205 and it is true.

But, if car is heavy and easily bring tires to the operating temperature pretty quickly (and even exceed it in some cases), that car will benefit greatly from wider tire as long as it fits on the rim. In our case, we can easily heat up even 285s and if it will fit on the rim it will be faster than 245s every time!

Now, with R-comps, operating temperature window is much narrower compare to the street tires we are using here, so that creates some interesting differences. You can have two or even three tire widths that would fit inside that temperature window, so they would both be working well. On Hoosiers which are much more sensitive to this, usually you have only one size (thanks to the limited availability of the sizes as well) and in some cases two of them that would work.

Other things that affect this is driving style as well and for more aggressive drivers wider tire might be better choice for given driving skill level.

Also, it is known that wider tire on the same rim will be moving more than the narrower one, which can/will cause some changes in car behaviour. Typically, response is slowed down a bit, but most of it can be compensated with steering and car placement. So, some of those side effects are tolerable and they will not bite you as much as some people think they will - well at least on car like EVO, which is pretty quick in that department.

So, in shortest form, if you can heat it up quick enough (like 1/3 of the first run), you are good to go with given width! If your tires get too hot after 1/2 the run, you could use something that tolerates heat better - being either wider tire or tire that can handle heat better.

Fedja

 

yes a lot of factors than just the tire width and the wheel width contact patch that affect it. the general mindset of nats guys (now that all the street classes are on street tire) learning from the ST classes is that in general, tire width is optimally within an inch to matching the width of the wheel. how fast they heat up is a factor, weight, rolling resistance/power, driving style etc all the things you mention. in general, closer to wheel width is better. some tires just aren't designed to be pinched either.

 

Mark Dadio decided in the last minute to run AS instead of SSR this year. He got a set of RS3s and decided to go pretty wide (295 and 275) compare to everyone else in that car (next Corvette was running 275/255 combo, I think). Even without any additional testing aside from what he did in Lincoln in those few days before the competition, he won easily. If he spends a bit more time with that setup, I bet he will be even faster.

That general thing you mentioned from nationals guys is mostly from low power and low weight ST cars that makes perfect sense for them. Heavier and higher HP cars don't fit into that one...

 

that example does nothing to prove or disprove your point. im not saying you're wrong, you may very well be right, but the only way to know for sure what's faster and what's slower and what works for whom is back to back same day same driver testing.

 

I guess I just need a set of 245s, 255s, 265s, and 285s (ZII are only there at this time) to compare against my 275s and we would be all set!!

 

You're talking about Mark Daddio. The guy is a winning machine. If it was some mid-pack hack that got into the top 3, it might lend more creedence to your argument.

Exactly.

 

No question about Mark and what he can/can't do! Of all of the aliens out there he is always at the top in my book.
But, other guys are not that bad either (from both AS and SS) and considering extremely limited amount of time he had to work with that car on given tires that he never ran, it is pretty safe to assume that he will be even faster in that car on the same tires in the future. He was asking for recommendation on tire pressures on Monday before the event. To still pull it that well tells a lot about his setup and his ability to use it.
As of convincing anybody here, I wrote what I think about it. You could like parts of it, the whole thing or none of that BS. Until there is some more testing done with it it is not easy to say. I know one thing though - if Hankook makes RS3 in 285/30/18, I would make sure I try it on my car! Might even try ZIIs for the same reason just to see what is going on there. Your mileage might vary.

 

And I wouldn't say Daddio won "handily". The margin of 3/10s is still pretty close to our local Ryan Otis who is an alien in his own right. Our region also doesn't get any practice on Concrete so there's a constant adjustment every time we travel to a national event.

That said, 3/10s doesn't really put a nail in the coffin of 295s vs 275s in that class on that wheel size.

 

Well, another interesting fact is that Mark just got that car and raced three times with it on street tires. Twice with PSSs and once on RS3s. It is reasonable to expect that he will be much faster after a short while. ..

 

To be fair, I think we all know Mark needs about 1 time in a car before he's fast