Naj: Sorry, I missed your question at first. The rims are standard MB 6.5 X 14 from an S class sedan from the seventies, although the 6X14's off a 123 sedan would also have worked. The tires are Kumho 205-55-14 DOT rated race tires. They were heat cycled and shaved prior to having them installed. They, along with the koni shocks made all the difference in the world for handling.
The kumho's are DOT rated, but are intended stirctly for track events. The tread wear rating is very low. Even if they were not shaved, I doubt anybody could get 5,000 miles out of a set if street driven.
I did two days of track driving and covered about 50-60 laps of 2.5 miles each lap. I competed against a 230SL a 1974 Euro 280SL and a 1973 450SL. The only 107 SL which had a better lap time was a 1980 450SL 5.0, at 2:05, which was in a different grouping of cars.
My best prctice lap was just under 2:09. The fastest lap period was a brand new SL55 which lapped the track in 1:48.
Great fun!!
Pete Lesler