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03-18-2011, 07:53 PM | #23 |
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03-19-2011, 06:14 PM | #24 | |
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The approved rim width for a 225/40-18 tyre is 7.5 to 9.0" and the approved rim width for a 255/35-18 tyre is 8.5 to 10.0". |
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03-19-2011, 11:13 PM | #25 |
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To the original question; is there a down side of the larger sizes? Yes, there are disadvantages. There are also advantages. The issue is, are the disadvantages significant. I have not seen evidence that would indicate one way or the other for the sizes mentioned. As the section width of the tire exceeds the rim width, there is more lateral flex and you need to plan for more clearance to struts and fenders. As the tire width increases in general, there is more of a tendency for the tire to track, e.g., toward the raising side of ridges, as in truck ruts. Potential disadvantages. As the tire size increase, the contact patch gets larger; although at a decreasing rate. An advantage.
Also note that not all tires measurement are the same. A stock Bridgestone RFT has a rounded shoulder and relative narrow contact patch compared, for example, to a Yokohama S.Drive of the same size. I think Gill said the same of the Hankook. I have seen many autocross and road race cars go for the largest tire for the specified rim width to maximize the contact patch. I have seen the "hot shoe" take the day on narrower tires. In race conditions, the contact patch usually wins. My observations. |
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03-29-2011, 09:40 PM | #26 |
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I don't know if you've already pulled the trigger on your purchase, but if you are thinking about going with non-RFT's and keeping the stock suspension, I think you will be disappointed with the high speed lateral instability and slop of that combination. I know I was.
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03-30-2011, 08:58 AM | #27 | |
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04-05-2011, 07:00 PM | #28 |
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Based on my experience in a 335i, I think he's referring to the slop in the stock suspension that suddenly shows up when you move to non-RFTs.
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04-06-2011, 03:06 AM | #29 | |
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I agree with this statement too. IF you are gonna keep the stock suspension - they stick with run flat tires in the OE size. The steering response is very good with the run flats. I am still happy I went with Michelin PS3's. But the steering response isn't as good as with the Dunlap run flats the car came with. The PS3's aren't that bad - but not as sharp in steering as the OEM run flats. But the better ride is really nice and the overall perfoamace is very high. Plus I plan on installing a //M3 suspension bits this year. Dackel |
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04-06-2011, 08:48 AM | #30 | |
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04-06-2011, 06:26 PM | #31 |
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Hate to thread jack, but if you lower your car will 225/40-18,255/35-18 fit with out modifications? I want to go with H&R super sport springs. should I keep the stock sizes?
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04-17-2011, 11:47 AM | #33 | |
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I was really impressed with these tires. I made the right choice... |
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04-17-2011, 11:53 AM | #34 | |
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The car seems to ride nice like that. Plus I do so much high speed driving (over 100 mph) that I like the way the car feels at speed with higher tire pressure. I was surpised my tire shop also used the same pressure when I picked up the car. Here are some pics of my PS3's. I don't know what they are called back in teh states. But over here Michelin does make another even more high dollar/euro tire called the PSS: Pilot Super Sports. Maybe you can tell by the tread pattern. ? Dackel Last edited by Dackelone; 04-17-2011 at 11:58 AM.. |
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04-17-2011, 09:41 PM | #35 |
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I have often wondered if the odometer is affected by larger diameter tires. As it does the speedometer. With 225/255s you may record less mileage, and therefore extend the warranty a small amount.
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04-18-2011, 07:33 AM | #36 |
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Actually, I found, via comparison with GPS, that the speedometer and odometer read optimistic (ie: fast) on the oem tire size... Going to 255 in the rear brought it to near perfect...so no more excess speed shown on the speedo and no more odometer clicking away too fast for the mileage.
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04-18-2011, 04:05 PM | #37 | |
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You might remember I had my car coded with the M3 digital speedo ("v = kph) that reads true vehicle speed. I have checked it against my GPS and the M3 speedo is dead accurate. The car's speedo reads high by about 3 or 4%. After I installed my Michelin PS3's in 225/255's I notice my digital speedo now read slightly slower, by about less than 1 kph. That is not something someone would notice if you ask me. For instance before when I would drive at 100 kph looking at my M3 speedo... the car's speedo would be reading about 104 kph and my GPS would also read 100 kph. Now after the new tires my speedo will read 103 kph and my digital speedo will read 99 kph while my GPS reads 100 kph. Again not somthing to get all worried about. Dackel |
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04-18-2011, 04:34 PM | #38 |
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No, they are different tires.
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04-21-2011, 05:22 AM | #39 |
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after talking to the boys in service (who are honest and i know well) they say that putting on the wider tyres on the fronts stress the PSteer and even causes issues with the ABS.
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05-24-2011, 01:16 PM | #40 |
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I had purchased 225/255 Michelin PS2s, based on advice from Gill's FAQ post, to install in my OEM 313 rims, but no one in Stuttgart, DEU, will install the tires on the stock rims. Does anyone else have experience with mounting 225s on 7.5 and 255s on 8.5s?
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05-24-2011, 04:29 PM | #41 | |
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i don't know what to say... the wheels are within the specs of the tire... it's a question of whether the tires are within the published or allowable specs for the wheel/vehicle. here in the states there's no problem mounting whatever tire you want (often regardless of whether it be a good or bad choice haha) |
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05-26-2011, 03:23 AM | #42 | |
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05-26-2011, 05:37 AM | #43 | |
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Originally Posted by royrathbun I had purchased 225/255 Michelin PS2s, based on advice from Gill's FAQ post, to install in my OEM 313 rims, but no one in Stuttgart, DEU, will install the tires on the stock rims. Does anyone else have experience with mounting 225s on 7.5 and 255s on 8.5s? Quote:
royrathbun - The problem is that for the German TUV they say the max size tire you can mount on the rear 8.5 inch wide wheels is a 245 - when they look up the info in their tire/wheel books. My tire shop also pointed this out. But I also told them I do not have to go thru TUV since I am in the Army (with German cover plates and all). Then they were Ok with doing it. It is only 10mm's anyway. I would tell your tire shop what you want to do. I would go to a shop that is near a US Army base and I bet they are more willing to do this or have done this for us Ami customers. I used ReifenWagoner (tire chain) - IF that helps you at all. Dackel |
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05-26-2011, 10:35 AM | #44 | |
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