http://pub.nikkan.co.jp/uploads/magazine_introduce/pdf_5465b...
From the above, we can tell キャクター is actually キャラクター, and R means ライン.
Since "character lines" seem to be all protruded, it doesn't seem necessary to translate 凸.

「プレス加工の限界に挑んだとまでいうボディのキャラクターラインは、シャープかつ大胆な陰影を生み出し、特徴的なシルエットを際立たせている。」
http://lexus.01-auto.com/is/news_tag/ボディライン
"The character lines running the length of the car from the double arch grille to the aerodynamic tail spoiler gives the vehicle its assertive look from front to rear."
http://www.autoblog.com/2015/01/11/infiniti-q60-coupe-concep...

If this refers to a tire, "ｷｬｸﾀｰ" is probably "character" as mentioned before, and "R" usually refers to the radius of curvature, so I am guessing that the radius of curvature of the protruding character is ground using the #100 sandpaper whetstone. More context would help.

an idea