Kentetsu

Thanks again for all of the input guys. I just finished up two days of racing, and fortunately, the new Sumitomos that I put on a couple of weeks ago are finally broken in. I easily won my class on both days. Today I got beat by a supercharged miata, a Westfield (lotus) and an STI, both on race rubber. But there were a lot of very nice cars there.

This weekend I finally felt like I was back on the top of my game mentally. Last weekend I felt like I was always a step behind, and my tires just felt very slick all over the course (only had about 100 miles on them). The car ran great, handled great, and I was able to milk her for all she was worth.

I'll continue to keep an eye out for a set of used race rubber though, just in case another extremely prepped Miata shows up to race in my class. lol. One of our club driving instructors gave me a very nice compliment today, telling me how much he enjoyed watching my runs. He said I was always right on the edge in the sweepers, holding just the right amount of drift, and that it looked like my car was "dancing" its way through the cones. It was a very nice weekend at the races.

Kentetsu

Here's a video from this past weekend. My car is the red fb, also the internal camera. External shots are pretty shakey due to having to use lots of zoom (pretty big lot).

http://www.youtube.com/watch?v=ZKNjkywj1Q0

Kentetsu

The final results have been posted for last weekend, and I was 2.7 seconds slower than the fastest time. I had a 59.4 and the supercharged Miata had a 56.7

So I guess the question is, how much tire do I need to make up a difference like that considering what I'm currently using for tires?

I think I'll be looking for a set of used Hoosiers.

rx7racerca

iTrader: (1)

The problem with used Hoosiers is they go "off" so quickly - many suggest they are best within their first 20 autocross runs, and heat-cycled out by 60, even if they have lots of rubber left. So tough to buy used, but if someone's giving some away...

710's last a fair bit longer before heat-cycling out - my most recent set got roughly 120 runs then noticably dropped off in grip (they likely had lost some already, but it was quite noticeable at that point). I'm a quite smooth driver and seem to have a good suspension setup (tires wear very evenly), but most people say 710s cycle out sooner, 80-100 runs.

R888/RA-1s aren't a great autocross tire, but they do last better than 710s or A6s, grip is more like the top sticky street tires - Direzza Star Sports or RE-11s or Kumho XS. They will not deliver the same class of grip as 710s or A6's, but can be a decent tire for local events, depending on how large or competitive your local club is - and they certainly beat having no rubber. They are certainly better than some other road-racing r-comps, like Yoko A048s that don't seem to deliver even top street tire-like performance used in autocrossing.

That said, I just picked up a set of R888s from a road racer with three heat cycles in them (I was told, in any case), and lots of rubber left for the 1/3 cost of new 710's or R888s. I can't afford new 710s, couldn't find used ones, and because they can heat cycle out before cording out, would be reluctant to pay much for used ones anyway, so the R888's will get me through the summer with local events, I may attend one regional and see how I do - I did ok in my class at one last weekend on seriously done 710s

Carl

iTrader: (2)

I just had a direct back-to-back comparison of Sumitomo HTR 200 (treadwear 380) and Dunlop Direzza Star Spec (tread wear about 200) at a Chump Car race. Driving 1st Gen RX7 in approximately Spec7 form. Tried brand new Sumitomo's and they were like driving on ice from the beginning. Lap times on Fontana infield course were low 1:40's. They didn't really change (for better or worse) throughout my 1-1/2 hour stint. Next session had brand new Dunlop's and the difference was absolutely night and day. Immediately laptimes were in mid 1:30's. I think my best was 1:35.9. Again the tires didn't change throughout the session. The grip of the Dunlops was not quite up to RA-1 or R888 levels, but surprisingly not a lot different.

The Sumitomo's were 205-60-13 and Dunlops were 195-55-15. For a combo tire I strongly recommend the Dunlop. They are cheaper than either Toyo. Of course, it is not available in 15" size. From a grip point of view, the Toyo's will be better than the Dunlop's and waaaaay better than the Sumitomos.

Kudos on your excellent driving on the Sumitomos. Get the Toyos and you will feel like you are in a rocketship. I'm sure the other more expensive tires maybe even faster, but they are also a lot more expensive.

Carl

Kentetsu

Thanks for the info guys (and the compliments)!

Carl, one thing I've learned with the Sumitomos is that they just don't work until you've got a few hundred miles on them. When new, they are extremely slippery. The difference between a race in June (about 100 miles on them) and another race one week later (about 500 miles) was night and day.

I rode in dj55b's car after a race a few weeks ago, and his 888s felt amazing! They were pretty well warmed up at the time though. So, I'm still thinking that a set of used Hoosiers (or v710s if I can find them) may be my best bet at a cost of around $200.00 I don't think it will matter a whole lot if they aren't as good as brand new tires, as long as they are almost as good.

Considering how close I already am while using the Sumis, I don't think I'll need all that much more performance in order to do what I want. I only need to pick up a couple of seconds on a 60 second course, and I think used Hoosiers will get me that with a little to spare.

The reason that I've stayed with the Sumis for so long (5 years) is because I wanted to work all the bugs out of my driving, and the car, before I made that final leap to race rubber. I think I've reached that point now.

Hyper4mance2k

iTrader: (40)

I've driven Miata's with R88's on them and they're damn amazing compared to any other street tire. Right not you're likely to find cheap used 710's and Hoosier A6's on the forums as everyone is buying tires for nationals. Check the IT forums and SCCA forums. I've run 710's and Hoosiers on my FB and the Hoosiers are better than the Kumho's.

Best way I can put it was on Dunlup DZ101's I was .5" slower than my closest competition then with 710's I was beating him by a .1 and with the hoosiers .2-.3