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03-22-2015, 08:25 PM | #23 | |
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03-22-2015, 09:54 PM | #24 | |
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I have 18 x 9 +45 and I had to mildly roll the rear guards. |
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03-23-2015, 07:56 PM | #25 |
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I'm actually not sure, since it only rubbed over fairly hard compression (over big dips or large speed bumps). No real tire wear noticeable either..
Last edited by Adam135; 03-23-2015 at 08:37 PM.. |
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03-30-2015, 08:44 AM | #26 |
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The best size tire on the 135i is as wide as you can fit. The car is severely under-equipped on tires from the factory. You can add 30-40mm front and rear if you plan well.
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03-31-2015, 10:40 PM | #27 |
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04-01-2015, 12:40 AM | #28 |
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To add to the conversation. On ST coils, I'm running:
F:18 x 8 +45, 225/40 w/ 5mm spacers R: 18 x 9.5 +45, 245/35 As far as I can tell the balance feels a little better when pushing 6-tenths or 7 tenths. But since I'm as low as I can go in the rear, the outside sidewalls rub the rear fenders on large bumps. There is about -1.5 deg of camber in the rear but only -0.5 in the front since I'm so low. I bet that if I started pushing the car to its limits the understeer would still be there. A nice set of camber plates or a stiffer front sway bar will reduce the roll and help the front tire maximize its contact patch.
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04-01-2015, 08:09 AM | #29 |
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You lost me when you say worse for turns. Unsure where that came from.
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04-01-2015, 10:46 PM | #30 |
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As in the car would handle better with smaller tires. What benefits dose a wider tire have. Obviously more rubber on the road but unsure if say a 265 rear would be better for our car than a 255 or vise versa.
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04-02-2015, 12:08 PM | #31 | |
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Your reply made no sense in the context of my post, so I don't understand what you are trying to convey from a basic communication standpoint. You might as well have replied to my post asking, "so, is cheese tasty?" It doesn't make sense.
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Last edited by Freon; 04-02-2015 at 12:19 PM.. |
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04-02-2015, 02:30 PM | #32 | ||
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04-02-2015, 02:33 PM | #33 | |
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The size of the patch is determined by weight on the tire and the pressure. |
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04-02-2015, 03:25 PM | #34 |
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Like most things in life, it is not as simple as MightyMouse suggests. It is a decent observation that a wider tire may not have more road contact since the length of the contact area may decrease but it turns out that the tire construction is also a significant factor. A tire is not a ballon or an inner tube. It has significant structure to it that also affects the road contact area. Check out this link:
http://www.performancesimulations.co...tire-pressure/ The wider tire in this case had higher contact area under most of the test conditions. That data is for only one pair of tires but my guess, I'll admit this is a guess, is that it is generally true that you will add some road contact by increasing tire width. But not as much as the width change might indicate. MightyMouse's argument isn't a perfect predictor but has merit. Jim
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04-03-2015, 09:12 AM | #35 |
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Jim, thanks for saving me the time. I've actually seen that article before and that's one of the ones that has informed my opinion on this very subject.
Tires do not behave quite like Physics 101 would lend you to believe, they're actually quite complicated. Of course optimal width could depend on what your specific goal is (the optimal width will be different for track, autocross, off-the-line acceleration, fuel economy, top speed, etc), but in general I think the 135i has enough weight and power for me to stick my neck out and generalize that you won't find the "too wide of a tire" point until you've seriously hack up the car to fit an absurd wheel/tire package. Can you go too wide on a 2200lbs 160hp Miata? Probably. On a 3400lbs 300-450hp 135i? Good luck with that. The gut check for someone new to this is to look at high performance cars. 650hp Corvette ZR1's don't come with 225/35/20's for a reason!
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Last edited by Freon; 04-03-2015 at 09:17 AM.. |
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04-03-2015, 05:46 PM | #36 |
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My rears lasted 8700 miles, while the fronts still had 60% life remaining.
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04-03-2015, 06:27 PM | #37 |
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I don't know the miles only because I haven't looked. But I have the same size tires on all 4 wheels on my 128i. I did that partially so I could rotate front to back. The other reason was to reduce understeer. The front wheels are half an inch narrower but still capable of holding the same tires as came stock on my sport package e88.
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04-03-2015, 08:46 PM | #38 |
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I think you have right foot issues.
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04-03-2015, 09:20 PM | #39 | |
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There is one thing that helps visualize better what is going on. Don't think of the rim being held UP by the sidewall. It is more similar to the rim actually hanging from the top of the tire like a suspension bridge. |
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04-03-2015, 10:01 PM | #40 |
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With the average flash tune/jb4 running 400+ft/lbs of torque on a soft high performance tire I think that's pretty typical. With the smaller front tires you also tend to weight the rear tires a little more though turns. It's just so hard to not put your foot down every now and again.
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04-19-2015, 12:42 AM | #41 |
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FYI, I try with both M sport pkg suspension with 225/40/18 and 255/35/18 no rub.
Also just installed yellow konei + HR spring with 225/40/18 and 255/35/18 no rub. |
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05-01-2015, 04:11 PM | #42 |
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whats the deal with increasing width and NOT decreasing sidewall aspect ratio?
i would think a 245/35/18 would upsize to a 255/30/18 and 215/40/18 would upsize to 225/35/18 unless these sizes don't exist Im about to pull trigger on some new Michelin PSS - running oe wheels with 15mm spacer in front and 12mm in rear on eibach springs. any input would be greatly appreciated |
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05-01-2015, 07:50 PM | #43 |
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Do it!
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05-18-2015, 07:45 PM | #44 |
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Bit of a side discussion, but does anyone have anecdotal experience with upsizing and the fronts being less susceptible to pot hole damage? I'm betting moving away from runflats alone will help with that too.
Had a car with PSS 225/40/18 for 11 years and I don't remember them getting as beaten as the stock fronts on our cars do. Thanks. |
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