http://www.changemytyre.com/car/up-size-car-tyres/porsche/tyre-upsize-for-porsche-porsche-boxster

Tyre Upsizing options for PORSCHE – Porsche Boxster

Original Size: 235/40 R18

Tyre upsize options in +0 Inch up for PORSCHE Porsche Boxster

No Option No Option No Option
No Option
No Option
No Option

Tyre upsize options in +1 Inch up for PORSCHE Porsche Boxster

No Option No Option No Option
No Option
No Option
No Option

Tyre upsize options in +2 Inch up for PORSCHE Porsche Boxster

No Option No Option No Option
No Option
No Option
No Option