Studded tyre having grooves

A tyre comprising:

• a tread comprising tread blocks such that grooves are arranged between the tread blocks, and studs installed into at least some of the tread blocks, wherein:
• a central region of the tread is arranged between a first shoulder region of the tread and a second shoulder region of the tread, the central region comprising a circumferential central line of the tread,
• the tread blocks define:
• a land portion of the tread, the land portion comprising parts of the tread blocks and the studs arranged to contact a ground surface when the tyre is in use, the land portion having a total land area, and
• an envelope surface comprising the land portion of the tread and the regions defined by the openings of the grooves, the envelope surface having a total envelope area,
• the land portion of the tread comprises:
• a central land area being an area of a part of the land portion of the tread that belongs to the central region,
• a first shoulder land area being an area of a part of the land portion of the tread that belongs to the first shoulder region, and
• a second shoulder land area being an area of a part of the land portion of the tread that belongs to the second shoulder region, and
• the envelope surface comprises:
• a central envelope area being an area of a part of the envelope surface that belongs to the central region,
• a first shoulder envelope area being an area of a part of the envelope surface that belongs to the first shoulder region, and
• a second shoulder envelope area being an area of a part of the envelope surface that belongs to the second shoulder region, wherein:
• a central land ratio of the tyre, the central land ratio being defined as a ratio of the central land area to the central envelope area, is 1 to 30 percentage points greater than either or both of:
• a first shoulder land ratio of the tyre, the first shoulder land ratio being defined as a ratio of the first shoulder land area to the first shoulder envelope area, and
• a second shoulder land ratio of the tyre, the second shoulder land ratio being defined as a ratio of the second shoulder land area to the second shoulder envelope area,
• at least some of the tread blocks of the central region are provided with sipes, such that the tyre has a first density of sipes, the first density of sipes being defined as a total length of the sipes arranged in the central region divided by the area of the central region,
• at least some of the tread blocks of the first shoulder region are provided with sipes, such that the tyre has a second density of sipes, the second density of sipes being defined as a total length of the sipes arranged in the first shoulder region divided by the area of the first shoulder region,
• at least some of the tread blocks of the second shoulder region are provided with sipes, such that the tyre has a third density of sipes, the third density of sipes being defined as a total length of the sipes arranged in the second shoulder region divided by the area of the second shoulder region, and
• the first density of sipes is at least 15% greater than either or both of:
• the second density of sipes and the third density of sipes,
• at least a part of one of the studs is arranged in a stud hole provided in one of the tread blocks, and
• no part of any of the sipes-is arranged closer than 6 mm to a center of the stud hole;
• wherein the tyre further comprises at least one ply, at least one metal belt, a cap layer forming at least part of a running surface of the tyre, an underlayer comprising a first rubber compound, and an intermediate layer comprising a second rubber compound, the intermediate layer being arranged, at least partially, between the underlayer and the cap layer, wherein a position of a tan delta maximum of the intermediate layer and/or the second rubber compound is configured to be between −40° C. and −70° C.;
• wherein a position of a tan delta maximum of the underlayer and/or the first rubber compound is configured to be between −10° C. and +15° C., determined according to ISO 4664-1:2011 in compression;
• and
• wherein each stud of the tyre comprises a base flange, a waist, and a second flange, and parts of the intermediate layer laterally surround at least some of the waists.