Now i know i recently placed a thread on the forum relating to various tyres but i have a question on wheel sizes and their asscociated tyres, so i currently have a rear wheel with a 200 x 18 tyre and who ever fitted it to the wheel on the bobber that i'm putting together didnt take into consideration the space available within the swinging arm so I want to remove the 200mm tyre and replace it with a 180mm so the question is will I need to change the wheel or will a 180mm tyre drop onto the current rim.