thanks ben for the information.
We as a vendor also recommend staying true to some of the OEM Characteristics.
for example, it is nice to go wide on the rear but if you go too wide on the rear, it will affect the handling characteristics of certain cars.
Cars like Porsche that are rear heavy will benefit from a wider rear with more rubber. M3's are closer to being 50/50 weight distribution. Therefore, even if it is a rear wheel avid drivers will benefit by staying with a difference of about 1 to 1.5 inch between the front and back. Some of the track guys that we know try to put as much rubber in the front as possible.
someting to consider as well...