Q. The number of revolutions per km for a free rolling tyre are less than that calculated from its static radius. This difference in number of revolutions is due to

• (A) forces in the contact area that cause slight forward of the tread
• (B) hysteresis of the tyre materials which make the dynamic loaded radius somewhat larger than the static radius
• (C) either of (A) and (B) above
• (D) none of the above