Front wheel size.

[Deleted account 111026]

When checking the front 19" 'snowflake' type rim on my project bike, I found it's marked 2.15 rather than the usual 1.85. I'm pretty sure it came of a 1978 R100RS but I can't find a model that used this size as standard.
Any ideas, please?
Also, does anyone know of a 'snowflake' type 18" rear wheel, drum type, of 2.75" width? Apparently an R100CS used this width rim but only with a rear disc.