[syko.xero]
Member
I am gonna run my 03.5 in the local autox this weekend in the "stock" class and wanted to know what would be a good tire pressure setup to run front/rear (temp in the 30s-40s
Autocross tire pressure
- Thread starter [syko.xero]
- Start date
I run 48/50 psi front/rear.
The front pressures may be higher than other people might run, but I'm trying to prolong the life of my tires (this is not a concern of competative autocrossers, I only do it for fun). The high rear pressure gives the car real neutral behavior (equal tendency to oversteer just a bit rather than understeer) entering corners.
It should be noted that I run the Dunlop 5000's on a Pro5.
The front pressures may be higher than other people might run, but I'm trying to prolong the life of my tires (this is not a concern of competative autocrossers, I only do it for fun). The high rear pressure gives the car real neutral behavior (equal tendency to oversteer just a bit rather than understeer) entering corners.
It should be noted that I run the Dunlop 5000's on a Pro5.
rocketspeed
Member
- :
- 03.5 Mazdaspeed Protege, Titanium Gray
Wow, that's high pressure. Do folks usually run pressure like that in an auto-x? I have no auto-x experience whatsoever.
The tire pressure you run depends on a lot of things. For example, the tires, the surface you run on, the course design and how you drive. I have been autocrossing for >35 years. Lately we have been running on asphault, more open courses and I used 38-40 fr and 32-34 rear. In general if the course get tighter, I raise the rear pressure more than the front. If you look at the TireRack web site, they have a good set of instructions on when and how to change the tire pressure.
When I run on grippy concrete, the tire pressures are higher all around. This is with the stock Bridgestone 040. The Dunlop SP9K's on the MP3 took more pressure on the same surface.
You need to watch the sidewalls of the front tires and see where the scuff marks are. If they go off the tread then you need to add air. If they stay too far on the tread, then you need to lower the pressure. Once you get the front working the way you want, adjust the rear pressure to get the feel that you want.
I know that is not a single answer but it may allow you to develop your own. I hope that it helps.
When I run on grippy concrete, the tire pressures are higher all around. This is with the stock Bridgestone 040. The Dunlop SP9K's on the MP3 took more pressure on the same surface.
You need to watch the sidewalls of the front tires and see where the scuff marks are. If they go off the tread then you need to add air. If they stay too far on the tread, then you need to lower the pressure. Once you get the front working the way you want, adjust the rear pressure to get the feel that you want.
I know that is not a single answer but it may allow you to develop your own. I hope that it helps.
Delivery_Guy
ProfessionalWarrantyUser
- :
- MSP
Last event of the season up in MN I started out running my normal 45 front 32 rear...almost did a 360 in the slalom. Dropped it to 38 in the front and the rear to 30. This seemed to work alright, but my limited experience is that the stock Potenzas really don't like cool weather, so keep that in mind.
But really, Dolphin is right, watch the side walls and they will tell you what pressure you should be running at. Marking a few spots around the tire with chalk can help you see how far down the side wall you are rubbing.
But really, Dolphin is right, watch the side walls and they will tell you what pressure you should be running at. Marking a few spots around the tire with chalk can help you see how far down the side wall you are rubbing.
Dialed in my pressures on the stock Bridgestone RE040s this spring: F38 R35. The car felt very good all season, but the tires are better when its cooler than 75 degrees out. Warmer than that and the RE040s get greasy and lose traction. I won street tire class for the season, beating a couple of WRXs. Eight times.
You want the scrubbed area on the front tire's shoulders to just come down to the edge of the tread, but not to get onto the sidewalls. You can use white shoe polish to mark your front tires shoulders, start at 40 lbs all around, and lower the front air pressures as you see how much shoe polish is being rubbed away. Bring the rears down even with the fronts until you have the fronts where you like them. Then, I like to reduce the rear pressures about 3 lbs lower than the fronts to add a little oversteer.
Oh, and go out and buy an accurate air pressure gauge. A 2 inch dial, 0 to 60 lbs, with a one foot hose and bleeder button by Longacre is about $20 and well worth it. I checked a friend's Honda S2000 tire pressures and what his digital gauge said was 32 lbs was actually 25 lbs!
Have fun!
You want the scrubbed area on the front tire's shoulders to just come down to the edge of the tread, but not to get onto the sidewalls. You can use white shoe polish to mark your front tires shoulders, start at 40 lbs all around, and lower the front air pressures as you see how much shoe polish is being rubbed away. Bring the rears down even with the fronts until you have the fronts where you like them. Then, I like to reduce the rear pressures about 3 lbs lower than the fronts to add a little oversteer.
Oh, and go out and buy an accurate air pressure gauge. A 2 inch dial, 0 to 60 lbs, with a one foot hose and bleeder button by Longacre is about $20 and well worth it. I checked a friend's Honda S2000 tire pressures and what his digital gauge said was 32 lbs was actually 25 lbs!
Have fun!
dolphin said:
Great answer, Michael! I use 40's up front and then 34-35s for the rear when I autocross on our asphalt parking lot/broken off runway.
The SP9000 did me well until MY last autocross event. Tread was almost gone from it and I spun out 3 out of the 4 times I think. The second run was my only good run (but still not good enough to land higher than 7th place) and then it went down hill after that. :mad:
mazdaowner123
Member
I see. My friend said 32 F 38 R to induce oversteer, but I guess he was wrong? This is a good thread.
scapamouche
Member
I prefer a looser setup, so I run more stagger between front and rear. On the RE-040s I generally run about 45f/ 31-33 r.
I have seen lots of roll over on the RE-040s, hence the really high front pressures...
R tires are a bit different: Victoracers lower in front (42-44) and about the same in back, and Ecsta V700s about 55 f and 35 or so in back...
I have seen lots of roll over on the RE-040s, hence the really high front pressures...
R tires are a bit different: Victoracers lower in front (42-44) and about the same in back, and Ecsta V700s about 55 f and 35 or so in back...
Allen,
Did you actually cord the tires? Usually when they go that bad that abruptly, it is because they have worn through to the cord. The first set of SP9K's on the MP3 were worn as smooth as a book cover and still working great. The instant they wore through to the cord you could feel the tires go away. The second set of SP9Ks is still going strong. Of course Heather is not as aggressive as I am.
conekiller,
32 PSI is too low in the front unless you are running on ice or something like that. Here we ask the novices to start with over 35 and suggest that they start with 40 PSI and work down. In some cases such as our concete lot I suggest that 45 PSI is a better start point expecially for the front. Unless you have Falkens or the DOT "R" tires you really need to start high, watch the side wall or use the shoe polish trick and adjust them down. It is much faster and easier to let air out of a tire than to put it in. I have an air tank and an air compressor but I still over inflate the tires to start with. Perhaps I am just lazy.
scapamouche,
If The MP3 is any indicator, then on our concrete lot, my pressures would be near yours. Depending on the course design, I might even go higher in the rear than in the front if I want to be able to throw the rear around. The Falken Azenis also have a stiff sidewall and usually require less pressure.
What ever pressures you start with, find an experienced autocrosser to help read your tires. This could be the same one that is helping to mentor you in getting started.
In any case, remember to have fun.
Did you actually cord the tires? Usually when they go that bad that abruptly, it is because they have worn through to the cord. The first set of SP9K's on the MP3 were worn as smooth as a book cover and still working great. The instant they wore through to the cord you could feel the tires go away. The second set of SP9Ks is still going strong. Of course Heather is not as aggressive as I am.
conekiller,
32 PSI is too low in the front unless you are running on ice or something like that. Here we ask the novices to start with over 35 and suggest that they start with 40 PSI and work down. In some cases such as our concete lot I suggest that 45 PSI is a better start point expecially for the front. Unless you have Falkens or the DOT "R" tires you really need to start high, watch the side wall or use the shoe polish trick and adjust them down. It is much faster and easier to let air out of a tire than to put it in. I have an air tank and an air compressor but I still over inflate the tires to start with. Perhaps I am just lazy.
scapamouche,
If The MP3 is any indicator, then on our concrete lot, my pressures would be near yours. Depending on the course design, I might even go higher in the rear than in the front if I want to be able to throw the rear around. The Falken Azenis also have a stiff sidewall and usually require less pressure.
What ever pressures you start with, find an experienced autocrosser to help read your tires. This could be the same one that is helping to mentor you in getting started.
In any case, remember to have fun.
mazdaowner123
Member
Could someone please explain the shoe polish deal? I know you mark the sides or something, but what does it tell you? Thanks a lot.
~brian
~brian
Brian,
Since the scuff marks on the tire can stay for a long time, it is sometimes difficult to determine exactly where the tire is rolling over to on the tread. So some people use a dab of white shoe polish at several places around the tire at the very edge of the tread. This way you can more easily see where the tire is running. You can also renew it easily every run or every event as you desire. The disadvantage is that your tires now have white shoe polish until you can get it off. It is not always easy to get the shoe polish off. Does this make sense now?
Since the scuff marks on the tire can stay for a long time, it is sometimes difficult to determine exactly where the tire is rolling over to on the tread. So some people use a dab of white shoe polish at several places around the tire at the very edge of the tread. This way you can more easily see where the tire is running. You can also renew it easily every run or every event as you desire. The disadvantage is that your tires now have white shoe polish until you can get it off. It is not always easy to get the shoe polish off. Does this make sense now?
i usually ran my pressures at about 33lbs f and b. that seemed to work pretty good.
i love watching those wrx people squirm when they get beat by a fwd car....
i was wondering if anyone knew of any tires that work well at autox and normal driving.
the potenzas aren't doing it for me...
i love watching those wrx people squirm when they get beat by a fwd car....
i was wondering if anyone knew of any tires that work well at autox and normal driving.
the potenzas aren't doing it for me...
Excitmnt94
Member
- :
- 2003 VW GTI 1.8T
i always try and run a couple less in the back than in the front. i had it set at 42-40 at the last event and did quite well. the wear was right where i wanted it to be.
and yeah...those WRX's have a lot of understeer going on. that being said the one i saw compete in the last event had only competed once before...so im sure with more practice he will get certain things straightened out.
and yeah...those WRX's have a lot of understeer going on. that being said the one i saw compete in the last event had only competed once before...so im sure with more practice he will get certain things straightened out.
mazdaowner123
Member
dolphin said:
That makes perfect sense. Thank you very much!
~brian
dolphin said:
Well, it was getting there. No cord, but I did see the wear line show through.... it had been showing through for several weeks prior to my last autocross event. Each run I went through I adjusted the tire pressure, started out high then went low.... and then even lower than what I was comfortable with at the time (I believe it was 35s front and maybe 35s rear).... still spun out bad. Just couldn't get a grip around the cones.... when I had to step on the brakes going STRAIGHT so I could enter the sharp slalom.... my car just slid straight into the grass .... immediate DNF... I was so upset that day, because I felt like the course design was perfect for my car to shine.... :mad:
It's all good though, Michael. 
I'll probably get a set of smaller wheels from either Keith at Flying Miata or Mach III sometimes next year. They've given me good options. I may check out the MX-6 wheels like you suggested to me... no need to modify them, right? Fits on perfectly to the MP3? Thanks.
I'll probably get a set of smaller wheels from either Keith at Flying Miata or Mach III sometimes next year. They've given me good options. I may check out the MX-6 wheels like you suggested to me... no need to modify them, right? Fits on perfectly to the MP3? Thanks.Allen,
You should have seen my first autocross in the MSP. You would have thought that I had just gotten my driver's license and from a very lax tester. I got so enthraled listening to the turbo spool up on the little straight that I almost missed the turn and then took out a wall of pylons making the turn when i finally woke up.
The MX-6 (and the 626 and Milleniun) used the same 5 x 114.3 bolt circle as the 5 bolt Protege. Their off-set was close enough to work and some looked nice. No I didn't have to modify them to get them to fit. They also make good wheels for the street and for snow tires. Not that either you or I have to worry too much about snow.
CUL
Michael
You should have seen my first autocross in the MSP. You would have thought that I had just gotten my driver's license and from a very lax tester. I got so enthraled listening to the turbo spool up on the little straight that I almost missed the turn and then took out a wall of pylons making the turn when i finally woke up.
The MX-6 (and the 626 and Milleniun) used the same 5 x 114.3 bolt circle as the 5 bolt Protege. Their off-set was close enough to work and some looked nice. No I didn't have to modify them to get them to fit. They also make good wheels for the street and for snow tires. Not that either you or I have to worry too much about snow.
CUL
Michael
