Do you have 18 or 19" wheels? You would probably be best suited looking for 18" wheels for your winter tires. If you already have 18" then perhaps you should use those for your winter tires and buy some new 19" for summer. MTM makes bimoto wheels that will fit the R8. There are a number of other wheels that fit based on advertisements that I have seen. For example OZ wheels are available through www.tirerack.com in the USA. This may give you a place to start searching.
Bolt pattern is 5-112. The problem with the R8 is getting wheels that will fit over the large brake calipers. You will see at Tirerack how few wheels are available for the R8. I'm trying to get some 18" Kinesis wheels made for tracking. I am awaiting word from the manufacturer if they can make their specific wheel while accommodating the larger R8 brakes. I am wanting the 18'" wheels/ tires because it allows for many more different hi performance track tire possibilities.