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[Bomiz]

Just installed 255/285 today, i'll let you know how it is.

[cenix]

Originally Posted by dahherwang

After did a search in forum, I found that most of members here choose 255/275 and 265/295 rather than 255/285...I am curious about the main reason of this phenomenon, does it really cause by the overall diameter difference? Or simply because 285/30/19 is still not prepared by Michelin PSS?

The primary reason behind equalizing the front and rear tread sizing for our cars is to mitigate the understeer. Lots of people like the meaty tire look, too. If handling were truly a priority, a better, stickier tire in stock sizing (like AD08R or RS-3) would out handle most of the meaty setups with Michelin PSS or similar types of tires.

[dahherwang]

Originally Posted by cenix

If handling were truly a priority, a better, stickier tire in stock sizing (like AD08R or RS-3) would out handle most of the meaty setups with Michelin PSS or similar types of tires.

Certainly true, but the question is the OE size tire(245/265 combo) is definitely not the optimal size for style 359 rim due to the width difference even though it can still be fitted with no doubt. On the other hand, if the 245/265 combo is the only one consideration of the designer, then a set of rims with 8.5J/9.5J width is good enough just like style 220 rim, what's the real propose for coming out a wider rim as style 359? Thanks and best regards.

[cenix]

^ Two things come to mind in regards to your question:

1. Cost - larger tires will be an added cost
2. Performance - to preserve quick handling repsonse

Of course I don't work or speak for BMW ///M, but I'm fairly confident that these factors were considered when they chose the stock sizes for the M3.

[dahherwang]

Originally Posted by cenix

^ Two things come to mind in regards to your question:

1. Cost - larger tires will be an added cost
2. Performance - to preserve quick handling repsonse

Of course I don't work or speak for BMW ///M, but I'm fairly confident that these factors were considered when they chose the stock sizes for the M3.

I think both of us can agree that the low cost/high performance should be the ideal goal for a car maker's business benefit, but obviously the choice which BMW made for E9X M3 went against that.
1. Cost: 8.5J/9.5J combo is certainly cheaper than 9J/10J if we don't consider the manufacturing process difference(forge or cast) which definitely effect the cost.

2. Performance: If you want the tires to show their best performance, then the optimal width fit to the rims is certainly a must. For the 9J/10J rims, 255/285 combo is definitely the optimal fit according to most tire makers' web page information.