04-24-2018, 12:25 PM | #67 | |
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how was it? Any issues? I am think about going 223~235 on 17" rims all around for auto X. It looks like there is only 0.1" thread width difference between 225 and 235 for most tires, but there is big jump from 235 to 245 in thread width. If there is no issue with 245, I may try it. Otherwise, I will go with 225. |
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04-24-2018, 01:21 PM | #68 | ||||
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If you can afford to test the 245 and return them if they don't fit I would definately try that. |
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04-24-2018, 01:46 PM | #69 | |
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How was RE71? I heard that the sidewall is very stiff and I prefer stiff side wall for auto x. Stock MPSS was like a jelly at 48 psi in front. lol |
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04-24-2018, 03:11 PM | #70 | |
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Expect a noisy ride when the threads are mostly gone. |
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04-24-2018, 03:16 PM | #71 | |
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I was running 45~48 psig in front with MPSS. It wore down to sidewall when I put 42 psi. |
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04-24-2018, 03:31 PM | #72 |
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04-24-2018, 04:09 PM | #73 | |
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I was starting my 20 minute sessions at 32-33psi and I'd be around 40psi hot (most cases higher) by the time I came back to the pit area, these tires heat up super fast.. I wouldn't run more than 38-40psi cold, for street use, let alone a scrub session... I suppose autoX could yield a higher starting pressure (I've never done autoX) since you need your desired tire pressure right away, as opposed to track where you can warm up a lap or two, first.. |
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04-24-2018, 04:15 PM | #74 | |
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I used to put 50 psi in front when I auto x my 07 GTI. lol Tire does not heat up that much during auto x. You run for 1 minute and wait for 5~10 min. The pressure goes up maybe 3~4 psi. and of course, I lower it down to 35 psi for street use. |
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04-24-2018, 04:17 PM | #75 | |
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I actually lowered the rear to 35 psi (stock is 39 psi). I guess it's a combination of heavy front (it's almost 54:46 for x drive) and skinny tire with soft side wall. |
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04-24-2018, 05:58 PM | #76 | ||
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04-24-2018, 06:34 PM | #77 |
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04-25-2018, 08:39 AM | #78 |
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RE71s, 33 cold, 37 hot. 235-40-18 square. Xdrive 8AT. Sport+ in manual mode, shifted to 2nd and left it there. I found that the car shifting for itself was way too abrupt and it always did it at the worst possible times. I have taken it to three autocross events and two track days. I am pretty much in love with this car and I think it is doing amazing. I’m coming from Mini and I’m still trying to get a feel for this car, but I think it is already doing great . I learned very quickly that you do not touch the gas in the corner on this car! It always seems to be in its power band, no waiting for boost. Takes off from the line like a bullet. I feel like it’s just the right amount of power. We see people come in with 700 hp cars and it always looks like a struggle to control and you only need about a third of that power.
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04-25-2018, 10:42 AM | #80 | ||
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Your pressures are WAY too high. You need to be in the mid 30s if you want grip. Given that these tires have stiff sidewall, you don't need to run as high of pressure. Quote:
Get some chalk and mark your tires from the edge of shoulder tread block to the sidewall, so you can see how much rollover you're getting (will vary based on tires, camber, psi, etc). Then find the tread marker on the sidewall of the tire to see where the rollover needs to stop ideally. From there, you just adjust tire pressure and camber as appropriate. Having a pyrometer helps but I wouldn't worry about that now. Of course, if you don't have enough seat time, none of this should be your primary concern, but that's another point. BTW, for FWD, you want more pressure in the rear so you can get the rear to rotate easier. By adding pressure (and that much at that) to the front, all you're doing is introducing more understeer. No offense, but I think you need to start making friends at your local autocross who is national level or very competitive locally, because I get the feeling you're doing things without proper guidance or someone's feeding you bad advice. What clubs are you racing with in Chicago? |
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04-25-2018, 11:07 AM | #81 | |
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I do all the stuff you mentioned above. (checking pressure, marking with chalk...etc) I ran with CCSCC in rantoul, IL little over 2 yrs. I did about 20+ autocross event 7~8 years ago but I was not that competitive driver anyway. I did Autocross class they offered and I did learn a lot of what you explained. They do have several good drivers. For my current car, it's got MPSS. That side wall is soft. I started at 40 psi but it rolled down to sidewall. lol So I had to keep pumping up. It was stable around 45~46 after 3 runs. (peaked at 48) Rear was good at 35 psi. Maybe I will start with 35~38 psi next time see how far I wear down on the sidewall. Once I get RE71 later, I will try lower pressure. I saw couple of E90 M3 running 33 psi in front with RE71. So It will be good starting point. |
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04-25-2018, 11:16 AM | #82 | |
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For AX, I keep my tires (not just 71Rs and Rivals, but also the previous "it" tires before that like RS3s, SS ZIIs, etc) around 32-33psi hot (slightly lower in the back to help with corner exits). The fastest way to get better at AX is not to just attend more AX events, but to attend the test and tune days for those who campaign on a regular basis. Those guys will usually rent out a lot for themselves to set up figure 8s, slaloms, etc so they can fine tune their suspension and dial in their alignment on the spot for that particular surface. You'll get way more runs and get much better advice at these types of "events" as long as you're committed to testing various set ups on your car. |
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04-25-2018, 11:36 AM | #83 | |
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http://ccsportscarclub.org/ When I had MkV GTI, I had Kumho XS and typically ran 42~43 psi in front if I don't want to wore down to tire name. lol I understand your point of running mid 30 psi as much as popssible but if tire rolls down below thread block (down to erase tire spec labels lol), I couldn't go any lower. Again, it's most likely the driver. Also, I am running 100 % stock and no plan to adjust any setup. (no camber adjustment in front anyway) If I am that serous about it, I wouldn't buy M240. I would get Focus st or GTI for GS. Still, I do enjoy auto x and definitely keep doing it. |
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04-25-2018, 11:48 AM | #84 | |
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Yeah, back in the day, adding pressure was fine but the newer crops of tires don't do as well with those kinds of pressures. I guess it also helps to know that you're completely stock and plan on staying that way, since that would change the type of advice given, lol. Good call on the GS class, lol -- their PAX is soft. FS is a bit soft, too, but the 2-series is not competitive in that class. With regards to the level of competition and fun with modding a car, the ST classes are where it's at, imo. |
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04-25-2018, 11:53 AM | #85 | |
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Good to know. I will keep in mind. Maybe I should try 35 psi with MPSS and see how bad it rolls. |
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04-25-2018, 11:56 AM | #86 |
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Part of your issue is that you don't have enough negative camber, so you'll have rollover regardless. You could also be overdriving, so maybe take it easier than you normally would on your first run and incrementally ramp up your aggressiveness. When I instruct, I tell them to take it at around 70% on their first run because beginners still overshoot anyway (not that you're a novice). At any rate, the most important thing is that you're getting out there and having fun so as long as that's happening, the rest is just icing on the cake.
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04-25-2018, 02:39 PM | #87 | |
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07-09-2018, 03:50 PM | #88 |
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I did another Auto X couple of weeks ago.
Tried to stay as low as possible on front pressure (40~42 psi). Little triangle for wear mark is now gone. lol MPSS does not like hot weather at all. It does get greasy and sidewall gets even softer. I would say I have to pump up 45 psi hot to keep it rolling down too much. Can wait to wear down these tires and get RE71r. |
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