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05-24-2010, 04:53 PM | #1 |
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Track day tire pressure 18" stock tires?
Hi guys, my first track day tomorrow with my E90. What tire pressure is optimal? Its going to be 85 degrees here so the tires will be hot!
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05-24-2010, 06:33 PM | #2 | |
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05-27-2010, 09:45 AM | #3 |
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Assuming the OE street tires, you are probably going to find that something in the 38-42 range, hot, will be your sweet spot, but you will have to experiment. And you are right, start a few pounds below your target range, and check the pressures immediately upon coming off track. Just noticed this thread is a few days old, how did it turn out?
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05-27-2010, 12:19 PM | #4 |
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Actually it does - you need to be aware of what the max psi rating is for your tire. I would not recommend starting your pressure at 40 psi for the OEM PS2's for example which is max 50 psi - I usually started mine around 31-33 and after a session they generally get to around 40 and seemed to perform fine although the get a little greasy after 4 or 5 laps. I have seen tire temps start at 31-33 and go as high as 45psi which in my opinion is too high for this tire and this car which leads to premature wear and lots of oversteer (although that can be lots of fun )
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05-27-2010, 02:14 PM | #5 | |
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05-27-2010, 02:17 PM | #6 |
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I run my RA1 40-42 psi hot.
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05-27-2010, 03:02 PM | #7 | |
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I will be sure to tell the guy that got his tires to 45 that he is over driving his car He has tons of experience racing and probably the quickest driver I know. I am pretty sure he knows what he is doing..... Not sure what you drive, but if you want to start your pressure high - that's your prerogative. Glad it works for you, but I hope you don't blow a tire. |
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05-27-2010, 03:38 PM | #8 |
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I generally start at about 32-34 psi and aim for 40-42 psi when the tires are hot.I have seen pressure increases of up to 15 lbs from the crappy R888's when I had poor rear grip.Even at the low tire pressures cold tire roll over has not been much of an issue.
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05-27-2010, 03:42 PM | #9 | |
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I know what you are trying to say. I know many say increasing tire pressures by aprox. 10% above the cars specs. Again not all cars are going to have the same spec for the same tire. Unfortunately Theory and Reality are not often the same. I am not suggesting the info you have stated is not valid or accurate - just stating doesn't work in all instances and we are talking about M3's and their not exactly light. The driver's style is also going to have an impact as well - and that has nothing to do with over driving. |
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05-27-2010, 08:19 PM | #11 | |
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I don't think you can avoid the "greasiness" on a hot day. It's just a limitation of the design. If the air temp is 85, then it's likely to happen.
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05-28-2010, 07:19 AM | #12 | |
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But thanks for the info - I am sure some find it interesting - just doesn't answer the OP's question or seem to be the experience of the other track goers here. |
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05-28-2010, 11:27 AM | #13 | |
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I find that there are a lot of very experienced forum members which offer great advice based on real life experience on this forum. Sorry your not one of them. (and for the record, I don't care if my opinion or advice matters to other people, maybe that's the difference between you and I) It certainly doesnt take much to get you on the defensive - quite fun actually! |
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05-28-2010, 07:43 PM | #14 | |
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I usually start at 40psi front 36psi rear,anything less than 35psi hot I get serious front tires rollover then again autocross is a bit more extreme than road racing.hahaha I wouldn't start off at 30-31psi for such a heavy car... |
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05-28-2010, 08:33 PM | #15 |
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Ran Thunderhill last fall, it was easily over 92 deg F ambient. Started at 40 psi hot on PS2 stock 18s, got them down to 38 psi hot after couple sessions and stuck with that. Did not get significant shoulder/sidewall wear, so I probably could have gone a little lower.
Ran Laguna Seca this past Wed, cloudy and passing light showers. Started at 40 cold and pretty much left it there as I didn't run very hard in my sessions and was not gonna chance testing the limits in varying cold/wet conditions. Whatever temps you decide at, always look at your sidewalls to gauge how much deformation you are getting and adjust (small increments!) as necessary.
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05-28-2010, 11:19 PM | #16 |
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I target 40 hot back at the paddocks. Depending on the tire, the weather, the track - I may be estimating between a 5 and 10psi gain after a session. I've run both BFG-R1's and NT-01's and they both seem to get real greasy north 40, especially the R1's.
I've started my day as low as 28. But starting that cold - you have to warm them up (lap or 2 or more) before any fast laps. Then monitor the sidewall or use shoe polish. Unless you have a good pyrometer, not sure it's too useful (yet). Having said this, at your first event starting higher - even as high a 5psi above MFG rec could be a good thing. How'd it go?
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05-29-2010, 06:51 AM | #17 | |
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Perhaps you should go back and read your posts. Just because I suggested to not starting your pressures above the OEM pressures (which is my opinion, and apparently the opinion of others that have replied to this thread as well) for an M3 you get your knickers in a twist and get defensive and suggest that because someone is getting 10psi or so gain in their tires they are over diving their car. I have made no mention of your driving ability or lack there of nor have I suggested that the generic info you have posted is useless. I (and others) who have tracked their M3's have given our experience and recommendation that seems to work for this car. Your babel about operating temperatures etc is all fun and nice, but we are talking about M3's not FWD cars which you seem to have an fascination with. Perhaps you can relate to us your M3 specific tracking experience and the pressures and tires and set up of your car. I guarantee you that members here with find that info much more useful. You seem to like to hear yourself speak or see your words on a screen so make some thread and knock yourself out. Sorry I am not hanging off your every word but I can go to any tire manufacturing website or track site and get the generic info you provided over and over and over again. Please enlighten us oh wise one. Sorry for raining on your parade...... Bad attitude signing out! (someone please remind me where the ignore user option is for this site! ) PS - read through the threads, you will find that there is a lot of very experienced racers/lappers in this forum who can provide a wealth of knowledge that is very useful for our cars (I am in no way suggesting that I am one of them). In my experience learning from those that can and do, is much more valuable than any text book or marketing material. You never know you might learn something! |
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05-29-2010, 10:38 PM | #18 |
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Hahaha it's hard to get two M3 owners to agree on anything. Then again there are a bunch of threads on ruined front PS2's.
If you start at 28psi before the tires get hot and overdrive the car,you can get some serious sidewall flex that might lead to excessive tire wear on the outside shoulder. So it might be better to start close to the target psi and go down as required. |
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06-04-2010, 07:34 AM | #19 |
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There is a great article on tire pressures in Roundel...I think it is the one with the review on the new 5er...which is a great looking car BTW!
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06-04-2010, 09:21 PM | #20 | |
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Tracking at Summit Point Main, 70-80 degree day which started rainy and ended up warm & sunny. I started with +3psi over the manufacturer recommended pressures and it worked pretty well. I probably should have increased by 1 or even 2 PSI, there was just a hint of rollover scrub on the top of the sidewall.
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07-16-2010, 06:24 PM | #21 |
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07-16-2010, 08:22 PM | #22 |
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Well, I couldn't find window chalk here in Korea so I used whiteout. Works, just makes a more permanent white mark on your tires.
So cold PSI was 38, hot was 46L/45R PSI. Max load on my tires is 51. So I guess I would try to dial in a little more camber first? If I increase tire pressure by 1-2 PSI, I fear that I will be getting close to the max PSI of my tires. April 2010 issue of Roundel. Try this link: http://roundel.imirus.com/Mpowered/i...issue=7&page=1 I think this will only work if you have a BMWCCA membership. I will try to print and scan from work.
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