Patent ID: 8465210

Claim:
A rolling bearing unit for a wheel, comprising: an outer ring member that includes a flange portion which is formed on an outer periphery of the outer ring member and which is fitted to a vehicle body-side member; an inner ring member that is rotatably fitted in the outer ring member; and double-row rolling elements that are arranged between the outer ring member and the inner ring member such that the rolling elements are able to roll between the outer ring member and the inner ring member, wherein the flange portion includes a first flange portion that is formed on an upper-side portion of the outer periphery of the outer ring member, and a second flange portion and a third flange portion that are formed on a lower-side portion of the outer periphery of the outer ring member, wherein each of the first flange portion, the second flange portion and the third flange portion includes a bolt-hole that is used to fit the outer ring member to the vehicle body-side member, wherein the first flange portion is formed such that the bolt-hole of the first flange portion is positioned on a vertical line that passes through a rotational center of the outer ring member, and wherein an angle that is formed between a line that connects the rotational center of the outer ring member to a center of the bolt-hole of the second flange portion and a line that connects the rotational center of the outer ring member to a center of the bolt-hole of the third flange portion is equal to or less than 100 degrees so as to enhance a rigidity of the outer ring when the flange portion is fitted to the vehicle body-side member.