R Mackow

I do low and high spd. autox and an occassional HPDE event. At Pocono last April I enjoyed Hoosier A3S05s 275 Frt and 305 Rear on std. C5 wheels. I really had alot of fun.
It just seems like when I found the answer, they changed the question??? I have a boat load of C5 wagon wheels that I don't know what to do with.
Now I see that A6 in 305 are not available. Go to a 295? What are the options for std. C5 wheels(17X8.5 and 18X9.5)?
Another option is to go to a Grand Sport wheel and do 275/315 frt/rear. Since my C5 is stock, am I wasting my time? Does the stk. C5 have enough torque and HP to accelerate the 315 or is the rotational moment of inertia of the 17" 315s greater than the wheel tire combination I have been running and will I lose ground(lose time) by going to the 315?
Would a Kumho w/a rounded side wall be more durable(when sliding side ways) than the Hoosier?

VetteDrmr

Not sure exactly what you mean by slow and high speed autox, but I run with the local BMW group, and we run courses that range from 1st gear courses with occasional forays into 2nd, to courses that get into 3rd (last event clicked over 100 mph).

I have both stock C5 wagon wheels (275/305) and 17" GS repros (275/315) on Toyo RA-1s and V700 Victoracers with good results. I get a little more understeer with the 275/315 setup than the 275/305 setup (understandable) and haven't had any problems with acceleration.

HTH, and have a good one,
Mike

Gordy M

I have been running the A6 with 275/40x17 in the front and the 295/30x18 in the rears on stock rims for the last year and 1/2. I have a medium agressive alignment of -1.9 front and -1.2 rears with 1/32 total toe out in the front and 1/16 toe in in the rear. In the high speed events the Z06's will out horsepower you, on a technical course you can get within 1/2 sec of the class leaders. In the low speed events you should be close to the Z06's on most courses, in the tighter courses you have a chance to beat them with skill ( you run the course in first and they have to continually upshift and downshift). In an open spaces low speed, they will just bury you.

AUTO_X_AL

Gordy has done very well on this setup. The competition here in michigan is pretty tough too.

R Mackow

Thanks for the input. NCCC seperates low and high speed autox. The low speed evnets are held on asphalt parking lots(1st and 2nd gear and similar to the SCCA events.)
The high speed that I've done are at Summit Point/Jefferson circuit(3rd and 4th gear.) and about 105mph tops.
The HDPE events at pocono north course(20 minutes at a clip, see google video/not my car but fun to watch) I hit 90mph in the infield straight and 130mph on the "bowl". I ran in an intermediate group and had a blast. The C6s and zs pulled away on the straights but I had fun catching them on the infield. I have ben using an HP+ pad and have been going deeper in to the corners and braking harder. A couple of guys are using a carbotechs. Any recommendations?
Rotors are stock Raybestos for about $30/each.
My camber: frt. is -1.5 and rear -1.0. Frt is toed out and rear toed in slightly...I beleive total of a 1/16th. My car is also a street vehicle and the -1.5 frt camber is taking its toll on the inside edge of my BFG KDs.
Who seels the toyo RA-1s?

Gordy M

For Low Speed events, I run the HP+ pads and separate rotors, for the High Speed events, you might consider separate rotors and pads. I use the DC70 on the fronts and HP10's on the rear. Sort of makes up for not being able to run a brake proportioning valve in Group I. For Rotors use NAPA or Rock Auto.