| Flieger |
Posted
Monday, Sep 11th 5:30am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 8
Thousand Oaks, California, USA
1983 E21 320i,M10,5 speed Getrag overdrive,alloys,Alpinweiss |
I am taking my stock, daily-driver 1983 320i 5speed to a Porsche club autocross at a local airport. I have the normal size tires- 175/40/13;I think. I have 13 inch alloys. The tires are winston warriors with a wear rating of 320. What tire pressures should I run to get the maximum out of these pathetic tires?
-when these tires are done, I get good rubber-
Thank you! |
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| jdench |
Posted
Monday, Sep 11th 1:24pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 96
Sussex, UK
1979 E21 323i, 1998 E36 323i touring |
About 27psi, just keep letting air out until they get nice and hot and sticky (but not too hot, you don't want to burst your sidewall) |
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| BruceH |
Posted
Monday, Sep 11th 3:02pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 1008
Atlanta, GA USA
81 323 Baur, 85 745 |
FWIW I ran 37/34 for the two seasons that I won the class with the 323. |
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| imaradiostar |
Posted
Monday, Sep 11th 4:17pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 865
Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i |
I think that people often let their pressures go too low- in general I find that most tires will handle better with 35 than with 30 or less. Tirerack.com actually has an interesting page with pictures of tires rolling over a plate of glass. It's surprising how much underinflation can have a negative effect on wet traction and even the shape of the contact patch.
Race-specific tires need not apply!
jamie |
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| melloh |
Posted
Monday, Sep 11th 11:59pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 416
California, USA (San Jose)
1980 320is, 1991 318is |
I start w/ 35psi cold, and itll warm up to about 40. After every run I check to see where on the tire is it making contact. My es100's even has an arrow showing you how for to the outer wall you should be going. If I'm using part of the tire further out, then I increase pressure.
My theory... as low pressure as possible w/o passing that point. Chalk probably would help to read this... but i'm just too lazy. As always, I'm curious what the experienced track-ers say on my hack ideas. |
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| melloh |
Posted
Tuesday, Sep 12th 12:03am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 417
California, USA (San Jose)
1980 320is, 1991 318is |
oh yeah.... I forgot an exception to my lame little rule of thumb... esp w/ the high sidewall of the stock e21 wheel/tire combo. Even if the treadwear is on the spot, I still might bump the psi (but w/in tire manufacturer range) to decrease some tire flex. It's a compromise, and I guess it depends on driving style, and how the auto-x is laid out and all that jazz. |
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| redmist |
Posted
Tuesday, Sep 12th 6:16pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 954
NY USA
357i , 325i e30 turbo |
Make a chalk/white shoe polish mark on the tire from the sidewall to the tread. Inflate the tire after a run so that the mark gets rubbed off no farther down than just below the shoulder tread and no farther up than where the shoulder just starts to curve down. Make a new mark before each run and adjust accordingly.
Minor adjustment can be made to adjust front rear traction as necessary.
Feel your tires after each run. The temperature should be even across the tire. If not adjust camber. |
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| melloh |
Posted
Tuesday, Sep 12th 8:58pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 418
California, USA (San Jose)
1980 320is, 1991 318is |
Something I found to be very accurate and useful... a nice BICYCLE pump w/ PSI guage built in.
Good:
1) reasonable compact
2) Lightweight
3) pretty damn accurate reading!
4) easy to control 'fine-tuning' of psi
5) no need to worry about running out of batteries or
6) no need to worry about tank running out of pressure
Bad:
1) Uhmm... you have to pump it, not just stick it on and press a button
2) You might get an awkward eye from fellow drivers... they're just jelous they didn't think of it! 
I now keep one in my trunk as part of my 'emergency' kit. |
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| Flieger |
Posted
Monday, Sep 25th 2:45am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 11
Thousand Oaks, California, USA
1983 E21 320i,M10,5 speed Getrag overdrive,alloys,Alpinweiss |
Thanks for everyones' input! I had a great time. The car felt great. I used 35 psi front, 32 psi rear with the tires warm but not hot. I found the limit of the tires very quickly, with the 320 wear rating. The front was washing w-a-y out. It was fun, though, and I dont think the tires could go any faster, even though the BMW and I could. |
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| melloh |
Posted
Monday, Sep 25th 1:57pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 424
California, USA (San Jose)
1980 320is, 1991 318is |
Sweet! Wish I coulda joined you, but just recently moved out of LA back up to san jose. Did you have to compete w/ the minis? When I went w/ the e30 318is I was classed w/ the (non-S) Mini (4-cyl stock) and got third. Not as good as it sounds b/c I think there were only like 4 or 5 total, and I was 2.5 sec from 2nd, and a tad more than 3 sec from 1st place. If I'd been in the e21 (even w/ sportier suspension - so not stock) I'd probably have at least another second added on.
So anywa, now you just have to go to like 100 more auto-x's so you can justify new tires. OR, just get som cheap wheels (can fine oem turbines or basket weaves on craigslist or junk yards) and wrap them w/ dedicated auto-x tires. Do I hear a wheel spinning and a breathless hamster yet? |
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| redmist |
Posted
Monday, Sep 25th 7:38pm [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 964
NY USA
357i , 325i e30 turbo |
did you do the chalk mark thing? Fronts were probably under inflated relative to the rear. |
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| Flieger |
Posted
Tuesday, Sep 26th 4:59am [Edit] [Quote] [IMS] [View car] |
Member
Post nr. 12
Thousand Oaks, California, USA
1983 E21 320i,M10,5 speed Getrag overdrive,alloys,Alpinweiss |
This was a Porsche club event so I was in the X class. An E46 M3 won the class. A Dinan tuned E30 M3 was third. I was last, behind Corvettes and the Porsches.
The chalk was not necessary for this car- it is stock ride height and the tires never rubbed. On the Porsche, which is in the shop, I use shoe polish but try to keep the pressures up to stiffen up the steering and keep the car from squirming.
The E21 felt great with those pressures and it was fun. Next time I can bring the Porsche if I want to win. Then again, it is simpler bringing a more street-oriented car with better mileage and I can still have fun. The tires must go, though, and ... |
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