GS Class: Si Stock Rim - Best Tire / Size?

[BV1]

With reference to AutoX,

I am thinking 225/45/R17 on a Dunlop Direzza Sport Z1... or possibly the RE-01R but I like the wet traction of the Z1 and am willing to comprimise the 1% on Dry to the RE-01R to get the 20% more on wet.

What are you GS guys running?

-Steve

[honda93]

Originally Posted by BV1

With reference to AutoX,

I am thinking 225/45/R17 on a Dunlop Direzza Sport Z1... or possibly the RE-01R but I like the wet traction of the Z1 and am willing to comprimise the 1% on Dry to the RE-01R to get the 20% more on wet.

What are you GS guys running?

-Steve

A serious GS autocrosser will be on Kumho V710's or Hoosier A6's.

[BV1]

Oops I didnt calarify, we have GS and GS-R two mini classes in the same. One R compound one not. I will be running in the street tire class.

Still... size wise what did you go with? Wider isn't always better, it can cause pretty bad lift and roll on the tire if the rim is too small. For the stock Rim, 225 Max or 235?

-Steve

[honda93]

Originally Posted by BV1

Oops I didnt calarify, we have GS and GS-R two mini classes in the same. One R compound one not. I will be running in the street tire class.

Still... size wise what did you go with? Wider isn't always better, it can cause pretty bad lift and roll on the tire if the rim is too small. For the stock Rim, 225 Max or 235?

-Steve

A 245 will safely go on the 7" wide wheel.

[Blurry]

I used RE-01Rs last year for autocross in 225s and they were great.

[BV1]

Hmm what about 235/40 17's ? A 245 might cause some roll on stock rim, not to mention the 235 40, is 0.9 smaller then stock for better gearing.

-Steve

[honda93]

Originally Posted by BV1

Hmm what about 235/40 17's ? A 245 might cause some roll on stock rim, not to mention the 235 40, is 0.9 smaller then stock for better gearing.

-Steve

You Si guys can't hit 60mph in second, my LX can. The last thing you want to do is run out of gear faster, because you really don't want to upshift to third unless you have to.

[BV1]

^^Good point, but the difference would be very minimal anyways.

-Steve

[honda93]

Originally Posted by BV1

^^Good point, but the difference would be very minimal anyways.

-Steve

1" lower in overall tire height will put the Si from it's current 57mph or so to 55.

[BV1]

Oops I meant 0.9%.

-Steve

[honda93]

Originally Posted by BV1

Oops I meant 0.9%.

-Steve

In my science classroom, I'd hammer a kid for forgetting to label what unit he or she used when referring to something like Newtons or Joules.

Don't let it happen again.

[00R101]

Originally Posted by honda93

A 245 will safely go on the 7" wide wheel.

I recommend that you go staggered tire sizes 245 front and 225 rear. That's what I am running on my Si (Hoosier A6s). I got very nice and controllable rotation this weekend.

I am running 1/8" total toe out front, 1/4" total toe out rear and as much neg camber as the crash bolts will allow (about -0.8 front and -1.2 rear).

I don't think there are too many regional autocrosses where the Si will exceed 57 (YMMV) so I wouldn't worry too much about lower profile.

Regards,
Alan

[BV1]

Well, I scored some stock size rims, Motegi DPK 17x7's with 42mm offset, for cheap, $300. As a bonus the guy threw in some used R's, V700's 225/45/R17. They still have some life in them, so going to use them for the next AutoX.

-Steve