Tire question...
 

I just bought a 2004 Boxster and the tires that where installed are:
- Front - 205/50 ZR 17 93W M S (Continental)
- Rear - 255/40 ZR 17 94W M S (Continental)

Is it normal to have different sidewall heights?
Thanks

Yes, that is normal. Those are the stock tire sizes.

It is common for many owners to install a 225/45 on the front to reduce the stagger between the front and rear tires to reduce understeer.

Yep, those are the stock sizes. Many sports cars have different sized tires front and rear.

And in nominal terms 50% of the 205 mm section width is a 102.5 mm sidewall and 40% of 255 mm is a 102.0 mm sidewall. 45% of 225 mm is 101.25 mm. I say nominal because every tire manufacturer's sizes are a little different and the width of the rim the tire is mounted on also affects section width.

Many that track or AX their cars go with the wider (225) front tire. For DD/street, the 205's are fine