Tire/tire pressure setups for Auto-X???

F

FrozenMazda

Member

:

2003.5 Titanium Gray MSP #355

• Jun 1, 2005

• #1

Folks,

What's everybody running as far as tire choice and pressure?

For now, I'm running my stock set (RE040's) until they're bald. I have been running 40psi all around, but the shoulder is getting eaten up pretty good on the fronts. Next race I'm going to 45psi all around.

Anybody with the Kumho Ecsta MX's or the new Falken 615's???

 

M

monkeymsp

Member

:

03 MSP Mica

• Jun 12, 2005

• #2

39 fronts and 44 in the rear. Concentrate on smoothness in getting onto the throttle coming out of the turns. From the sig pic it looks like you went into that turn hot and were pushing and had to overcorrect. Another trick you can try is chalk your tire before a run. Just run a line from the tread stright down the sidewall toward the center of the wheel. Then after the run look to see how much chalk is gone. Increase your pressures until you are no longer rubbing the chalk off the sidewall. Also, remember to check your pressure between runs. I have seen the pressure in my tires rise by more than 5 lbs after a run.

Happy autoxing!

 

F

FrozenMazda

Member

:

2003.5 Titanium Gray MSP #355

• Jun 14, 2005

• #3

monkeymsp said:

...From the sig pic it looks like you went into that turn hot and were pushing and had to overcorrect. ...
Happy autoxing!

Click to expand...

Yeah. That was a pick from my first autoX last year. I'm doing a little better this time around. Somehow I'm third in points!!! (confused) The solo2 school my region put on I think is helping a bit.

Still have good tread and the 42 all aound on the RE040's worked pretty well. Ended up one place out of trophying last race. Putting in Dave's klunk fix tomorrow for my race on Saturday. Hoping that will help a bit. May also disable the ABS too.

 

E

evolv

Member

Contributor

:

Yelllow 2003.5 MSP

• Jun 16, 2005

• #4

Stock RE040's

I've been running 48 front and 40 rear. Spent a whole test day working on getting those pressures right. For me they work best. The car feels very neutral.

 

P

Prodigy

G15M-R guru

:

'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx

• Jun 16, 2005

• #5

Stock Petenza RE92's
40F/45R

I'm still playing with the pressures.

 

E

evolv

Member

Contributor

:

Yelllow 2003.5 MSP

• Jun 16, 2005

• #6

Prodigy said:

Stock Petenza RE92's
40F/45R

I'm still playing with the pressures.

Click to expand...

I have heard of others putting more pressure in the rear then the front, but that almost defies the laws of physics. The majority of the weight is in the front, and during braking you are transferring more weight to the front. So, with lower pressures in the front (especially around 40) don't the front tires take a beating when you transition from breaking to turning. I mean; until you apply gas and start to transfer weight to the rear would the load come off the front tires?

Also, does your car oversteer with those pressures?

 

P

Prodigy

G15M-R guru

:

'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx

• Jun 16, 2005

• #7

evolv said:

I have heard of others putting more pressure in the rear then the front, but that almost defies the laws of physics. The majority of the weight is in the front, and during braking you are transferring more weight to the front. So, with lower pressures in the front (especially around 40) don't the front tires take a beating when you transition from breaking to turning. I mean; until you apply gas and start to transfer weight to the rear would the load come off the front tires?

Also, does your car oversteer with those pressures?

Click to expand...

I'm not too sure about the weight transfer...
"You can increase oversteer by LOWERING the pressures in the REAR to allow the shoulders to roll more creating a more progressive oversteer. Cranking up the rear pressures will provide a smaller contact patch but result in "snap" oversteer." -Apexlater

My car understeers a bit thanks to the weak rear sway bar... so I have it semi-neutral now.

 

M

Macs MSP

Member

• Jun 16, 2005

• #8

Tires & Pressure

It's always helped me to put less pressure in the front tires than in the rear. It takes most of the understeer away and helps me kick out the rear when needed or give a more even progressive slide in fast slaloms.

I just changed out my tires from the stock RE040's to Pirrelli P Zero Corsa. The Pirrellis are ten times better. I started racing with them at the very end of the season last year and I was finnishing first in every race. They claim to be 140 treadwear like the RE040's but they are a lot softer. They pick up all kinds of crap off the road. I think Tire Rack has them at a decent price but they changed them a bit and I don't know if they still offer the same treadwear and size. I saw the new version on a couple Ferraris' about a month ago (in a showroom).

If any of you are looking for a AutX tire for your MSP look no further. The strange thing about the Pzero Corsas are, every other size except the 215/45/17s are racing compound. I'm now playing around with the pressure again because I was getting a little understeer last race. I need to check my pressure after every lap like someone sugested earlier... good advise by the way.

 

F

FrozenMazda

Member

:

2003.5 Titanium Gray MSP #355

• Jun 16, 2005

• #9

I've been having trouble with 40psi in the fronts. Tires seem to be wearing on the sidewall a bit, but 42 seems to work alright. Hoping to pick up a pyrometer tomorrow so I can also check tire temps at the end of each run. Supposedly the more even the temperature is from inner/middle/outer, the right pressure you have.

SCCA looks like it's outlawed the Pirrelli P Zero Corsa for STX class. Don't know if they make a distinction between sizes or compound (within the same tire name).

Just got my klunk fix installed last night. Looking forward to trying it out on Saturday's race.

 

M

mazdaowner123

Member

• Jun 16, 2005

• #10

Falken Azenis RT-215, 38-40 psi front/rear.

~brian

 

M

Macs MSP

Member

• Jun 17, 2005

• #11

P Zero Corsa

I can see where they can outlaw the Pzero Corsa in every size but the 215/45/17. Every other size other than this is race compound and a treadwear of about 80. SCCA rule book states that any DOT aproved tire which is 140 treadwear or higher is legal in street tire classes.

You have me worried a bit because those tires aren't cheap. Know one has mentioned anything to me here in Detroit.

Can you let me know where you heard or read about the P Zero Corsa?

Thanks,
Brian

 

M

monkeymsp

Member

:

03 MSP Mica

• Jun 17, 2005

• #12

evolv said:

... Also, does your car oversteer with those pressures?

Click to expand...

Our cars do well in Autox being a little loose in the rear. It helps turn in and recovery from tight courses. But it does tend to oversteer a bit. Remember "loose is fast"

 

M

moxnix

Owned by AutoX

:

90 Miata (AutoX Toy), 03 Spicy MSP

• Jun 18, 2005

• #13

Macs MSP said:

I can see where they can outlaw the Pzero Corsa in every size but the 215/45/17. Every other size other than this is race compound and a treadwear of about 80. SCCA rule book states that any DOT aproved tire which is 140 treadwear or higher is legal in street tire classes.

Can you let me know where you heard or read about the P Zero Corsa?

Thanks,
Brian

Click to expand...

I am looking at the PDF for the 2005 rulebook available on the scca website.

14. STREET TOURING CATEGORY

14.3 TIRES

D. Tire models must not appear on the following list, which may be
altered at any time by the SEB upon notification of the membership.

Pirelli P Zero Corsa


I have not looked at any fastrack to see if they have been removed from the list or not. You might want to check out the fastracks and see if the list has been changed.

Also since the 215/45 YR17 is the only one that meets the 140 rating that must be the one they banned. The others are not able to be run in the class at all based on the 60 rating.

I ran 44F/39R on stock MSP tires based on guesswork at the AutoX this morning (I normally run the miata but felt like killing the stock tires on the MSP today) It felt pretty good but I think I might want a little more pressure in the rear.

 

E

evolv

Member

Contributor

:

Yelllow 2003.5 MSP

• Jun 19, 2005

• #14

monkeymsp said:

Our cars do well in Autox being a little loose in the rear. It helps turn in and recovery from tight courses. But it does tend to oversteer a bit. Remember "loose is fast"

Click to expand...

Ya.. I know a girl that was loose and she was fast.....LMAO

 

L

low_psi

Member

Contributor

:

ms|slowtege #399

• Jun 19, 2005

• #15

42/40R. seemed to work well with new springs.

 

M

Macs MSP

Member

• Jun 20, 2005

• #16

Tires

Thanks for the info on the Pirrelli tires. I'm going to check the scca website tonight.

I have a bad feeling that you're right and they may not be allowed. It makes sense because they are a really soft tire for 140 treadwear.

I don't race until next weekend but I'll try the lower pressure in the rear tires and see what happens. I know that I didn't use enough pressure in the front tires last race. But the rear felt perfect at 40PSI.