Sparky

Finally got to try out the new 275/35-18 Hoosier A6s. Didn't have the opportunity to do a direct side by side, but here are my impressions (take it for what it's worth)

Tire fits well on the rim. Much easier to mount than 245 Kumhos.

Rear end traction dramatically improved over the 710s. Off the line it was very difficult to get any rotation. Same for wheelspin on turn exit, almost non-existent. IMO this offset the gearing disadvantage inherent in the tire, but first gear may become more necessary on slow elements.

Less happy with the front end. The car felt very tight and I had to soften up the front shocks and raise rear pressures to compensate. Ended up at 46F/48R with the front shocks at 50% to get the car reasonably neutral at higher speeds. 46psi was optimal in front with traction decreasing 3psi on either side. Rear pressure was on the high side of optimal to achieve balance. Looking back at my notes, I ran the same pressures with A3SO4s so it may just be something I haven't uncovered yet in my setup. Car is noticably less tolerant of slip angle on the front than with 710s. Once a push starts it's very difficult to correct because the rear is so planted. Don't know if the front sidewall is rolling or just typical Hoosier response.

Overall though, once I got the rear pressures where I wanted, the car was very tossable. Not as good as with 710s but much better than I remember the SO4 being. The rear end was very managable in high speed offsets, coming out just the correct amount with aggressive inputs. Cornerning speeds were increadible with less tendency to slide at the limit than with 710s. The car is at least as fast, probably a few tenths faster than with 710s judging by comparison with others running that day. It took the full 6 runs to scrub them in but by the end of the day they were plenty quick. Still have some setup work to do but IMO the 710 won't keep up once things get sorted out.

No doubt in my mind that 275 rears are the way to go, particularly for pro solo. The fronts might be happier with a 245, but then there's a whole nother set of problems associated with running stagger and keeping it in balance throughout the day. I heard Carter was running a 245/285 stagger a couple of weeks ago. Anyone know what we was on at Peru?

ULLLOSE

iTrader: (1)

I hear 285 f and r on 8 and 8.5 wide wheels. I guess it took like an hour per wheel to get them on. We tried last year with three guys and they could not get it on the SSR. I have never seen it on anything less than a 9 and even then it is super hard to do.

Cito

If the 285's are so stiff you can't get them on (or I guess barely get them on), wouldn't that make the contact patch strange? Assuming that these are V710's we are talking about.

Sparky

No, he's running A6s

Cito

Hmm, well that makes more sense that he could get them mounted. Would 285's still be a problem in terms of contact patch on an 8 inch rim? They are shorter in terms of ride height, which would alleviate some of that gearing issue.

ULLLOSE

iTrader: (1)

Yes he was on V710s.

I am not sure how wheel width effects tread width but I found a chart that says a 1/2" +/- change in wheel width, from the one the tire manufacture used for its spec, changes the tire section width .2"+/-.

So looking at section width for the V710:
245-35-18 9.8" on an 8.5" wheel per Kumho, should be 9.6" on our 8" wheels.
285-30-18 11.4"on a 10" wheel. So should be 10.6 on an 8".

So the 285 should have a 1" wider section width than the 245 on our wheels. However a bigger section width does not mean a bigger tread patch. Every time I have seen a small tire squeezed on a small wheel the edge of the tire is bent way over and the actual tire patch did not look any bigger. I could see on a camber challenged car having the shoulder bent up could help save edge wear and might aid grip in sweepers. However I would think it would make the tire have very poor response in transition.

Not to mention the 285 weighs 2lbs more then the 245.

Sparky

Well he was on A6s last month. Can't speak for Peru. Would love to have his tire budget.

TeamRX8

iTrader: (25)

275/35-18 is a mistake on an RX-8 ...

brattesani

i just picked up a set of a6's. gonna try em out on saturday.

clyde

They're selling those A6s for $845...10 runs on them IIRC.

carusoracer

I can not comment on the rim fitments with the Hoosiers'. But I can sure tell you that you need to be on "Fresh Hoosiers" more often than multiple run Kumho's

Anyone conducted any real back to back tire testing on "Asphalt" Kumho vs Hoosier?

Maybe UULOOSE can comment on impressions after this weekends event in Topeka?

Cito

How about a reverse stagger: 275's in the front and 245's in the back? I have asked about this before. It must be stupid because nobody even responded to the previous question.

RX8SpdDmn

Hey Sparky!

Thanks for the ride on Sunday. Those tires stick like crazy. Did you watch that Solstice run? wtf??!! I never watched him, but how did it POSSIBLY do that well on Falken Azenis'??!! He was a FULL second faster than you! Was he just an incredible driver? He took top Pax position.

June 3rd
http://teamtac.org/cgi-bin/mods/show...i?id=autocross

Please explain!

Sparky

You must have left early. That was Alan McCrispin (aka McConnell) multi-national champion and he wasn't in the Solstice for those run but had switched to Clay McCools fully prepped Miata on 710s. My last run was quicker than his but I spun it though the finish trying a stunt and took a few cones out.

Once the tires were fully scubbed and the setup adjusted, the car was capable of 63 second runs. Unfortunately, the driver just wasn't up to it.

RX8SpdDmn

Oh, ok.... I can sleep better tonight!!
I remember you saying you had hit a 63, but took out some cones. Dang... I wish I wasn't going to Barber on the 16th/17th so I could run w/ you guys again! lol, jk
Actually, can I come autocross JUST on the 18th? I may be available that day, since the DE is on Fri/Sat
I'd like to have you ride with me and see what you have to say.

John V

iTrader: (1)

I didn't respond because I just have no idea why you would want to do that. It's not like the car is lacking in its ability to rotate.

The 245/35 Kumhos work so well I just see no reason to change.

ULLLOSE

iTrader: (1)

I will let you know how used Hoosiers work on the new surface.