Quote:
Originally Posted by jgold47
Sorry to post this without doing some research first, but I just picked up a set of 19" staggered 63's, and when I was showing my wife we realized that A) the diameter of the fronts (255/50) was about .5-1" wider than both the backs (285/45), and the stock 17" on the car now.
The rears, the tires are shot, and the fronts the tires are relatively new, so could that PLUS tire pressure (not sure what they are set at), cause that discrepancy, or is something awry?
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I'm going to assume that you haven't grasped the full meaning of "staggered" wheels & tires yet....or you haven't grasped the calculation & interplay of tire width & tire aspect ratio in the overall diameter/circumference of a wheel/tire set up when the wheels have different widths but the same height.
Since this is slightly complex...and already written very well...check out a site like
http://www.tirerack.com/tires/tirete...jsp?techid=200 ...they do a great job in explaining width/height/aspect ratio etc of staggered wheels and/or a set of wheels/tires that are the same size on all 4 corners.
Staggered Style 63 wheels have fronts that are 9"x19" & rears that are 10"x19". As written on the chart on your door and the owners manual...BMW lists the recommended tire sizes for a straight or staggered set-up. As the tire gets wider...the aspect ratio gets smaller so that it retains the same rolling diameter/circumference. That's why the front & rear tires are different.
You can also input the tire sizes into a tire size calculator (try
Tire Size Calculator - Tire & Wheel Plus Sizing ) and get the specs for various tire sizes (input your regular 17 set-up as the base, then input the staggered 19" tire sizes...then compare).
Good luck, I hope this makes sense.