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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Wed, May-23-2012, 11:06:49 PM   #11
DemonicAW
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Default Re: Rear tires.... Need your advice plz!

No idea if I understand how things work. I went from 225f / 255rear to a 245f and 265r and I like how the car handles much better. Corners where I felt the front end was plowing now feel as though the front bites much better. I thought Id share.
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Old Thu, May-24-2012, 12:00:21 AM   #12
Foo2rama
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Default Re: Rear tires.... Need your advice plz!

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Originally Posted by DemonicAW View Post
No idea if I understand how things work. I went from 225f / 255rear to a 245f and 265r and I like how the car handles much better. Corners where I felt the front end was plowing now feel as though the front bites much better. I thought Id share.
Exactly, the rear end makes no difference when you go bigger in regards to lowering the understeer threshold. The point at which you enter understeer is dictated by front tire size (as long as the fronts are smaller) the bigger the front tire the higher turning force is needed to enter understeer assuming the same type of tire.

What you did was increase the size of the contact patch at the front which gave you more grip. Since you still had a grip bias towards the rear you did not lower the oversteer threshold.

The M3 is for all intents and purposes 50/50 weight balance, so a car with a square setup ie 255 all around under neutral throttle will neither understeer nor over steer but break grip equally and remain neutral. This car can be managed into either over steer or understeer by throttle and weight transfer. This is vastly simplified and suspension settings have an impact on this also... softer springs will tends towards more grip at the cost of increased weight transfer which is not always a good thing... but that is another discussion.


The larger the tire width and consequently the tire contact patch dictates how much grip you have at that corner. so a car with 225 fronts and 255 rears would enter understeer at the same speed as a car with 305's in the back...
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Old Thu, May-24-2012, 12:00:55 AM   #13
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Default Re: Rear tires.... Need your advice plz!

thank you very much !!!

be careful !!
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Old Thu, May-24-2012, 04:19:11 PM   #14
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Default Re: Rear tires.... Need your advice plz!

Thatsmy setup right now until I can afford the fronts. I have no issues mainly because im not taking corners at high speeds. If you plan on driving hard through turns then maybe you might need 245'sthe up front.
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Old Fri, May-25-2012, 01:12:11 AM   #15
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Default Re: Rear tires.... Need your advice plz!

Here's the pic requested on OEM E92 18" 245/45f 265/40r
On OEM Suspension
Sorry its a mess, once I get the coilovers on next week I'm gonna clay bar it and take some high res shots.
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Old Fri, May-25-2012, 01:15:44 AM   #16
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Default Re: Rear tires.... Need your advice plz!

I run 275 on all four corners.
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Old Fri, May-25-2012, 12:31:33 PM   #17
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Default Re: Rear tires.... Need your advice plz!

Is'nt there a problem with the speed sensors or something that effects the ABS and the speedometer accuracy when you put too much difference in tire circumference???
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Old Fri, May-25-2012, 01:27:35 PM   #18
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Default Re: Rear tires.... Need your advice plz!

Quote:
Originally Posted by DemonicAW View Post
No idea if I understand how things work. I went from 225f / 255rear to a 245f and 265r and I like how the car handles much better. Corners where I felt the front end was plowing now feel as though the front bites much better. I thought Id share.
The front bites better not because you went up a couple sizes, but because you're running one of the stickiest street tires available. Unless you compared 225 and 245 PSS front tires back to back your comparison is not valid. I'd bet money you went from worn out crap tires to new PSS tires.

For instance, my 225 PSS fronts bite WAY WAY harder than my 245 V12s could ever dream of.

On the street it's all about the tire, not the size. I run OEM sizing on both cars and the only time I get any understeer on the street is when I'm driving extremely recklessly - which is exactly when you want understeer. A neutral car is a dangerous car at the limit.
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Old Fri, May-25-2012, 02:15:43 PM   #19
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Default Re: Rear tires.... Need your advice plz!

Since we are on the issue of tires, I am guessing you guys are all running 275's in the rear and 245's in the front with no issues of needed to roll the fenders or hitting or anything? I have 19's with a 35 offset in the front and 33 offset in the rear.
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Old Fri, May-25-2012, 04:01:54 PM   #20
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Default Re: Rear tires.... Need your advice plz!

Quote:
Originally Posted by Foo2rama View Post
Exactly, the rear end makes no difference when you go bigger in regards to lowering the understeer threshold. The point at which you enter understeer is dictated by front tire size (as long as the fronts are smaller) the bigger the front tire the higher turning force is needed to enter understeer assuming the same type of tire.

What you did was increase the size of the contact patch at the front which gave you more grip. Since you still had a grip bias towards the rear you did not lower the oversteer threshold.

The M3 is for all intents and purposes 50/50 weight balance, so a car with a square setup ie 255 all around under neutral throttle will neither understeer nor over steer but break grip equally and remain neutral. This car can be managed into either over steer or understeer by throttle and weight transfer. This is vastly simplified and suspension settings have an impact on this also... softer springs will tends towards more grip at the cost of increased weight transfer which is not always a good thing... but that is another discussion.


The larger the tire width and consequently the tire contact patch dictates how much grip you have at that corner. so a car with 225 fronts and 255 rears would enter understeer at the same speed as a car with 305's in the back...
Noob question, I would like to understand better, what understeer and oversteer are?
Thanks.
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Discussing Rear tires.... Need your advice plz! in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)