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      03-31-2015, 09:18 AM   #1
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Unhappy confused helpppp:(

Hello everyone ..

Im confused in buying new tyres for my 640i coupe i had great deal for michelin tyres 3+1

free but they only have for front 255 35 20 and rear 275 35 20 ..

Where the original size for tyres are 245 35 20 front and 275 30 20 rear ..

Can this tyres fits properly????

Im so confused please help
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      03-31-2015, 10:52 AM   #2
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increasing or decreasing the width a bit isn't a problem, so the front tires won't change much.

increasing the height on the rear will make the tires look unusually thick, especially compared to the front tires. ideally, look for a 30 series tire, but if cost is very important, a 35 tire isn't too bad. tiny tiny drop in performance, but the rear fill feel smoother on roads with the increased height
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      03-31-2015, 10:58 AM   #3
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The front would be okay as the overall diameter difference between 245/35 and 255/35 is negligible at about 7mm. I do not think the additional 5mm width to the inside will rub as others have made this change.

The rear, however, is not good. Going from a 30 to 35 series with a 275 width increases diameter by over an inch (27mm). This will throw off your speed about 4% at 50km/h, but more importantly reduce the amount of torque you put down on the road by the same 4%. If you don't care about these things, I think it will fit, but your performance will suffer.
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      03-31-2015, 12:29 PM   #4
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245/40/20 front, 285/35/20 rear. You can do it.
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      03-31-2015, 12:43 PM   #5
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Quote:
Originally Posted by Downfourit View Post
245/40/20 front, 285/35/20 rear. You can do it.
Looks good, What type of springs do you have?
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      03-31-2015, 12:52 PM   #6
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Quote:
Originally Posted by Bönz View Post
The front would be okay as the overall diameter difference between 245/35 and 255/35 is negligible at about 7mm. I do not think the additional 5mm width to the inside will rub as others have made this change.

The rear, however, is not good. Going from a 30 to 35 series with a 275 width increases diameter by over an inch (27mm). This will throw off your speed about 4% at 50km/h, but more importantly reduce the amount of torque you put down on the road by the same 4%. If you don't care about these things, I think it will fit, but your performance will suffer.
^^ This
However, the standard rear tire of 640i coupe is 245/45/18 so the total diameter of rear wheel is 26.68" . with new tire (275/35/20) your total diameter would be 27.57" which is 0.9" or 3.3% larger than the standard wheel...
Your front tire is also 1.2% larger than standard which is negligible...
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      03-31-2015, 01:18 PM   #7
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Quote:
Originally Posted by vaio23 View Post
Looks good, What type of springs do you have?
H&R Springs
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      03-31-2015, 03:52 PM   #8
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Quote:
Originally Posted by M6-Coupe View Post
^^ This
However, the standard rear tire of 640i coupe is 245/45/18 so the total diameter of rear wheel is 26.68" . with new tire (275/35/20) your total diameter would be 27.57" which is 0.9" or 3.3% larger than the standard wheel...
Your front tire is also 1.2% larger than standard which is negligible...
Looks like he's starting from the 20" wheel package, not 18s. So he's going from 26.5 to 27.6 which is a 4% increase. Regardless of starting point, I think a diameter of 27.6 is too large. It will fit, but I wouldn't do it.
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      03-31-2015, 05:05 PM   #9
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due to my wheels being bent, car being low and subsequent rubbing, i tried 245/30, 245/35, 255/30, 255/35, 275/30, and settled with 265/35 on an 11" rim.

which is to say, if a tire mounts and beads safely, you're really worrying about small differences in performance and fitment. and by fitment, i'm referencing all things like the diameter which effects speedometer and rolling distance, rubbing if you're lowered, and the appearence of proper fit versus stretch versus fat tire looks.

and to be frank, unless you are doing timed runs, the performance changes are negligible. you lining up against an m4 or CLS63 isn't going to change
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