Autocross, what'r tires worth on a 30ish second course?

I'm getting better, but am I picking up ~2 seconds?  How close am I?

Tight course, fastest times were high 31s, low 32s, "average" fast in the low 34-low 35 second range.   Fast guys were all in hot rod 'Vettes and new 911 GT Whatevers.

And since I'm running V730s, I guess I can kinda sorta answer that question based on the tire tests with it v. the A052s, about a second and change, apples to apples size for size.

TL:DR, if I bump a size and run the "fast tires" am I picking up 1.5 to 2 sec on that course?

Longer version:

My Gala to Granny Smith comparo is a pair of STS guys in a 90 Miata, had to be running 225s, tires looked fat on those 7.5 wheels (I think if they were 8's, it be "normal" looking, and the car was billed as an STS car when it was listed for sale locally).   Not sure what brand tire, I'd guess 660s if I had to, but the dudes who run it usually run good stuff.

My Car (NB1) is STR, mostly since it comes with a Torsen, but I'm on 205s and 8s.

The STS cars fastest runs were  between 34.5-34.9, and my best was a 35.6.

If I were to run a 225/8 combo on 660s/71RS' am I running right with those guys?

I think I am, but would like to hear from the hive and it's real world experiences here when switching up.

You are close enough that a set of sticky tires would get you in the hunt. 

In rwd applications we've found V730s and RT660s in the same size to be about the same speed, though we preferred the way the V730s drove. So going from 205 V730 to 225 RT660, the performance increase would really just be the size change, possibly with a bit of a backwards step from being harder to drive. On that short of a course, probably a few tenths at most. Going to 225 RE71RS or A052 is going to be another step from the better compound, I'd guess probably about the same quantity. So probably around half a second, maybe a full second but that's probably pretty optimistic.

dps214 said:

In rwd applications we've found V730s and RT660s in the same size to be about the same speed, though we preferred the way the V730s drove. So going from 205 V730 to 225 RT660, the performance increase would really just be the size change, possibly with a bit of a backwards step from being harder to drive. On that short of a course, probably a few tenths at most. Going to 225 RE71RS or A052 is going to be another step from the better compound, I'd guess probably about the same quantity. So probably around half a second, maybe a full second but that's probably pretty optimistic.

Hmmm.  I think that puts me there - the lost time was from oversteer on a tight course.  As I disciplined myself (and had fewer instances of oversteer, and less severe), my times dropped.   Once I knew where not to overdrive the car, I focused on where else I could pick up time.

I'll spend the rest of the year looking to keep that discipline, and then the larger size should kick me up a little more.

There are lots of good resources to look at for a comparison like this. Tire rack for example has numerous tests between the ultra performance tires. Of course GRM itself has the incomparable AWH who has done numerous tests on the various different tires mostly track oriented recently. 
The breakdown typically goes tire compound, tire width, tire support. So get the stickiest tire possible like the Yokohama or the Bridgestone then get it wide as possible then get the rim wide as possible.

so you should have a 225 Yokohama on a 9 inch wide wheel for the stickiest compound and the best support. Or perhaps even the falcon RT 660 on a 9 inch wheel in a 245 width.  

One thing the testing shows is that from the fastest fast tire like the A052 to a medium fast fast tire like the V730, the difference is probably only about a third of a second on a 30 second course.

Getting good data as to where your benchmarks are faster might be most helpful. 
going from a 205 V730 to a 225 A052 is unlikely to get you that 1.5 seconds out of 30 seconds. 
Also think about getting a know good driver from a similar platform to compare 

In reply to Ando :

In time I'll step up in tire size at a minimum, and if I think I'm progressing well enough and have the spare cash, I'll run 9s, but I'm just trying to ball park how close I am before I do that.  

One guy was a 34.45, the other was 34.97, and I was a 35.62 with oversteer coming in to a section to accelerate.  Without the oversteer, I'm within spitting distance of the 34.97, but still a good ways from the 34.45.    And that 34.45 was that guy's flyer, the other times between the 2 of them were basically 35 flat to 35.2.

And I know where the 34.45 came from (I was working that corner) - on that course was a bit of left hand sweeper feeding right in to a 180 right just before the finish, and he just jammed on it.  He had that thing on rails coming round the left, had the braking perfect coming to that last cone/180, and poked it through the finish.  Similar enough platform, and I know where those guys were faster.

After all of my oversteer shenannigans (even on my best run, just a lot less of it), I didn't trust that last left, and was afraid to over cook the 180 right just before the finish.  

If I can stay within a half second of those guys pretty consistently the rest of the season (assuming I make the events), I think I'll move up to the better 225s in early spring.  Running them on 9s is TBD, depends on a couple factors.