SCCA Solo C Street Discussion

[jprice130]

Originally Posted by 7thgear

our local autocross organizers have Yokohama as a major sponsor.. we all might get really good deals on the AD08r.. but from what i gather this tire doesn't stand up to the price and utility of the new Dunlops or RS3s

thoughts?

I've scoured internet forums for feedback from top-level autocrossers on the performance of the AD08R, but I haven't seen much of anything. It seems the cost is just too far above the other tires in the category and the TireRack testing didn't seem to indicate they were any better than the Z2s, RE-11s, or Rivals. The 225/45/17 size averages about $40-$50 more per tire than the competition, so it just doesn't seem worthy of the plunge. If you can get them for a discount, we'd love to hear your feedback!

[G_Ride]

Originally Posted by jprice130

I've scoured internet forums for feedback from top-level autocrossers on the performance of the AD08R, but I haven't seen much of anything. It seems the cost is just too far above the other tires in the category and the TireRack testing didn't seem to indicate they were any better than the Z2s, RE-11s, or Rivals. The 225/45/17 size averages about $40-$50 more per tire than the competition, so it just doesn't seem worthy of the plunge. If you can get them for a discount, we'd love to hear your feedback!

Agreed.
@7thgear if you can get the AD08R for a price closer to what the other tires cost, it's worth trying out.

[simpleisbest]

Originally Posted by JRTritsch

BTW has anyone tried the Toyo in RTR? I'm leaning on trying both the Z2 and the Toyo next year but I won't bother with the Toyo if it will just get destroyed by the lack of camber.

I've tried it on our 7" rim. Grip was fantastic. Took a while to get used to the Toyo vagueness, but the times were there! Wear was shocking. I wouldn't consider running them for a full season, as they would not last. It would be interesting to use for a Tour event. The tire is fast and the grip is there.

225/45-17 size was tested.

For the Toyo to last as long as the Z2 or Rival, it needs to be squared up or even a bit stretched...with more front camber, IMO.

Now only if we had a a plus 1" in wheel width option instead of diameter...

[mrazny]

Originally Posted by simpleisbest

I've tried it on our 7" rim. Grip was fantastic. Took a while to get used to the Toyo vagueness, but the times were there! Wear was shocking. I wouldn't consider running them for a full season, as they would not last. It would be interesting to use for a Tour event. The tire is fast and the grip is there.

225/45-17 size was tested.

For the Toyo to last as long as the Z2 or Rival, it needs to be squared up or even a bit stretched...with more front camber, IMO.

Now only if we had a a plus 1" in wheel width option instead of diameter...

you wouldn't be in C-Street...

[simpleisbest]

Originally Posted by mrazny

you wouldn't be in C-Street...

Hmm...I think I read the rules. Why do you say that?

[Kido1986]

He's saying that an extra inch would move you out of C Street. I don't think he understood what you were actually saying.

[mrazny]

Originally Posted by simpleisbest

Hmm...I think I read the rules. Why do you say that?

If you think that the wheel allowance should've instead been +1 width instead of +1 height, then the cars would be classed accordingly. The SAC recommendation would likely bump the twins relative to other cars.

The Twins' gains for the extra inch would be more than other cars gains. the 7" is part of why the grouping is what it is.

[jetfire]

Originally Posted by 7thgear

if you go 18s with the proper rubber to go up a size, you're effectively raising your center of gravity

so i wouldn't see this as a benefit

16s on the other hand...

but i gather the tire sizes equal out anyway so there is no point

17s it is

i would imagine the increase in center of gravity would be negligible vs. the grip improvement you'd get from running 18's?

[7thgear]

why would you think you'd be getting any significant grip increase from going up to 18's?

which isn't to say there isn't.. but there are a few things that need to be kept in mind

the forumla isn't that black and white

[dsgerbc]

What center of gravity? If you keep the OD the same, you'd have the same CG.

The rotational inertia of the rim matters a bit. If you move the thick aluminium band of the rim's barrel within your tire/wheel combo an inch further from the center (somehow keeping the weight the same), you'd increase rotational inertia by %10%. I think it takes about 5-6hp to accelerate all four wheels at WOT. With 18" rim you'd have 0.5HP less going to toward acceleration. Peanuts, if you ask me.

Grip increase? Hm. Maybe a bit sharper turn-in, if you go with tires with lower sidewall, keeping the overall diameter the same.

[7thgear]

Originally Posted by dsgerbc

What center of gravity? If you keep the OD the same, you'd have the same CG.

the arguments are assuming the relative tire size goe sup along with diamater for a change in gearing.

[dsgerbc]

Originally Posted by 7thgear

the arguments are assuming the relative tire size goe sup along with diamater for a change in gearing.

I guess in practice you're right, there aren't any decent options of preserving the overall diameter with going to 18".

[simpleisbest]

Originally Posted by mrazny

The Twins' gains for the extra inch would be more than other cars gains. the 7" is part of why the grouping is what it is.

Personally, I think other cars in our own class will gain much more vs the twins with the current allowance rule and become much faster as a result.

I guess we'll find out this year how the SAC's wise decisions with regards to classing turn out. I think that we will have an uphill battle with the 370Z and only have a slight advantage on tight and heavy transition courses. It will be rough at many regions around the nation, including mine.

Needless to say, I can't share your faith in the SAC's ability make smart decisions and balance the classes. Just look at the poor souls with non-M3 BMWs in F-Stock/Street!! It looks like a virtual garbage dump sunday with the M3's on top.

[mrazny]

Originally Posted by simpleisbest

Personally, I think other cars in our own class will gain much more vs the twins with the current allowance rule and become much faster as a result.

I guess we'll find out this year how the SAC's wise decisions with regards to classing turn out. I think that we will have an uphill battle with the 370Z and only have a slight advantage on tight and heavy transition courses. It will be rough at many regions around the nation, including mine.

Needless to say, I can't share your faith in the SAC's ability make smart decisions and balance the classes. Just look at the poor souls with non-M3 BMWs in F-Stock/Street!! It looks like a virtual garbage dump sunday with the M3's on top.

had a long post, the site went into maintenance...

Classing is about strong classes, not doing the best for every submodel of car. If "A" bmw and "A" mustang are in the hunt, F Street did it's job.

The SAC job is huge, with SEB oversight and wishes along with balancing newer driver needs, established driver needs, overall parity, and quality of competition. Those are solid guys putting in a ton of work for whats a thankless job.

They do better than most give them credit for.

All i can say about wheel width or *any* rules allowance... be careful what you wish for. STX heavy cars wanted more wheel/tire, they got bumped to STU. There's just not room for everyone to get what they want unfortunately. NASA classing doesn't work.