Simple tire/rim size question

[jpw47]

Sport package equipped 325/328/330/335 have 1 size wider tires on the rear vs. the front. Are the wheels actually wider on the rear? Are the wheels from the front and back interchangeable? The wheels are specified with a single "type", but does the set come with wheels of 2 different sizes?
Thanks.

[StigNV]

Tires are wider on the rear with the sport package option, and are a staggered set, non changeable. However, you can get same size tires all the way around with the standard option package, and they are interchangeable.

[shifterkart33]

The wheels are wider in the back, not just the tires.

[brokenbimmer]

For the 335i sedan w/ sport: Fronts are 225/40/18 on 8 inch wide rims w/ 34mm offset. Rears are 255/35/18 on 8.5 inch wide rims and 37mm offset. The standard option is 225/45/17, 8 inch wide rims w/ 34mm offset all around.

I've done lots of research on wheels recently. This spring I will switch to D-Force LTW-5 17x8.5 inch rims (just 16 lbs each) all around. I plan on putting 235/45/17 General UHP tires (just 21 lbs each) up front and 245/45/17 Nitto NT 555R drag radials in back. This will save about 12 lbs of unsprung weight per corner, give a better ride, and next winter I can the same sized winter tires all around.

[shifterkart33]

I'm also planning to go with the same size wheels front and rear, 17x 8 in my case. The wider wheels on the back look good but I think any performance gain is offset by the heavier tire. I will probably add 1/2" spacers to the rear wheels to fill out the fenders a little better. My 255/40-17 rear tires and wheels weigh about 60 lbs and the front 225/45-17 front tire and wheels weigh about 56 pounds so I'll be saving almost 20 pounds each rear wheel and tire, for a noticable improvement in acceleration.