Maple Grove Raceway AutoX

[KPAero]

Nice, it's always fun to surprise people. That's pretty funny about the guy in a WRX thinking it was a Turbo. Were you using the Kumho's? I'd be interested in how they did in the wet.

[SwedeSport]

The Kumho's were incredible. Of course the drift event the day before blackened the parking lot for us. I was hanging the tail out all day and had a few hairy sideways drifts and saves, but even with standing puddles on course there was plenty of traction. The guy in the Sentra was running v710s and told me that the ecsta xs was the absolute best tire for a cold damp pavement. I wish I could find pics and vids from the event, as there seemed to be people shooting all over the place.

I ran the Kumho's at 45 psi. Marked the shoulders with shoe polish to gauge how much rollover I was getting. I was getting a little skip from the front tires, and the rear was hanging out a bit. For the next event I may reduce the fronts to about 42, and the rears to about 40 to see if I can tune out the skip and slide. Although dry pavement will yield a different result, I still think that the pressures were a bit high.

I dont have enough experience to compare them to other race tires, but my impression of the Kumho's is that it was money well spent.

[Geoff]

I'm a fan of low tire pressures. The sidewalls should be stiff enough to keep the tire from rolling over, you shouldn't need 45psi. Though it sounds like it worked out for you, keep up the good work!

[SwedeSport]

I have read that for autocrossing that you want to set your pressures 10-15 psi higher than for the street. I dunno whether that is so you have more than enough air, (being that its easier to bleed off air than it is to add it) or to reduce rollover. I had an air tank with me but didnt use it. The re-staging time was rather limited, and being a newbie I had enough to do to focus on the protocol. I'm gonna try running them a little lower the next time. The shoe polish on the tires was indicating that I could go a bit lower in the rear, maybe 5-7 psi, and I could probably reduce the fronts by a few psi too. Trial and error I guess.

[Jordan]

I think a lot of it depends on the sidewall stiffness of the tire you are running. I'd assume those Kumhos have pretty stiff sidewalls and don't need excessive pressures to keep them inline.

[Hans]

The only real way is to test, but you can cut to the chase by seeing what others who drive FWD cars *of similar weight* are running for those tires. Try www.sccaforums.com or maybe www.northamericanmotoring.com, www.honda-tech.com, www.grassrootsmotorsports.com, etc. (If you come across any info regarding adding a big front swaybar for FWD autocrossing, ignore it -- it's a crutch for camber-challenged strut cars. Because of their double wishbone suspension, c900s are faster without a front bar.)

FWIW, I used to run Falken Azenis at over 40psi in the front on my c900s.

If you're keen to improve and do a bunch more events, check this out: http://www.dmvrscca.org/topten.htm