I too think the 255s are a bit slim... One thought was to change to 275s all around, so that I make a rotation once. 275s are no problem on 9" rims. If you look at the tire mfg's specs, you can also fit 285s on a 9" rim, but the surface profile of the tire will be a little "over weight".
What do you guys think?

I too think the 255s are a bit slim... One thought was to change to 275s all around, so that I could make a front-back rotation once. 275s are no problem on 9" rims. If you look at the tire mfg's specs, you can also fit 285s on a 9" rim, but the surface profile of the tire will be a little "over weight".
What do you guys think?

The sport package 255/50 in rear just too narrow and I too want to change the rear to 285/45 but not sure if the 9" rim will make it look wider or have to chagne to 10" wide rim...

Here in Greece Sport Package comes with 20" 275/40 in the front and 315 /35 in the back.. my previous e53 had sports package with 19" 255/50 285/45 ... its a hall difference experience with the 20"......far far better!

[QUOTE=us_matrix;636306]The sport package 255/50 in rear just too narrow and I too want to change the rear to 285/45 but not sure if the 9" rim ("

Finding it hard to understand where eveyone is getting the 9" and 10" measurements from?,does the 9 and10" refer to alloy diameter? my 3.0d with sports package has 255/50 r19 front and 285/45 r19 at rear, am I wrong in guessing that 255 ie 255mm=10.03" and the rear being 285mm ie 11.2"

[QUOTE=omodos;847191]Correct, the 9" & 10" are the rim width. That fits the MSport 19s 255/50 front and 285/45 rear. For the monster 20's (275/40 front & 315/35 rear) requires 10" & 11" rims respectively. The tire width is always at the widest part and always wider than the rim. The rim width usually matches the tread width (shoulder to shoulder).

Here is a picture of a 175/80x13 tire on probably a 5"x13" rim.
See Tire Tech Information - Tire Size Guide of you're not familiar with the full tire sizing codes. Note the tire diameter and rim width are not part of the code, but the approximate diameter can be calculated.

I'll add that to find out "what size rim should I have for a given width/profile tire?", you go to the TIRE manufacturers specification page- they will list of allowable rim widths for any given tire. Your rim should be in that range.

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Ill add one more Tirerack link that has more explanation. And does mention about checking allowable rim widths. Tire Tech Information - Calculating Approximate Tire Dimensions
All of their detailed tire spec pages do show allowable rim widths.

This is how mine was delivered also. For the winter I keep the 214 style wheels but on 275s at each corner. Has worked fine so far.

ta for all replies ok will check out the calculators, but basically and i guess everyone is fed up of me asking, i want want to know if i can whack on the 255/50 r19 size tires onto the rear also and the rear is a 10J r19 alloy i.e 10 inch wide....as opposed to the fronts that are 9j 9inch.....