IN traditional BMW style, the standard tyre fitment is not all that's available. A 17-inch, double-spoked alloy wheel with mixed tyres can be optioned. Of course, the standard wheel is already 17 inches, which means BMW cannot option you into a larger wheel. If you want to go to 18 inches, buy an M3 - if you can find one. Happily, the spare wheel is full-size in the 330Ci, which is not always the case in sporty BMWs. The Z3, for instance, makes do with a can of tyre gunk BMW cutely calls the "BMW Mobility System".