Rubber composition and tire

A rubber composition,

• comprising at least one selected from polybutadiene rubbers or styrene-butadiene rubbers, at least one selected from the group consisting of carboxylic acid-modified styrene-butadiene rubbers and carboxylic acid-modified polybutadiene rubbers, and at least one compound containing at least one selected from the group consisting of metal elements, metalloid elements, and a nitrogen element,
• having a complex modulus E* that reversibly changes with water, and
• satisfying the following relationships 1) to 3):
• Complex modulus E* when water-wet/Complex modulus E* before water-wet×100≤98 1.
• wherein E* represents the E* at 23° C. of the rubber composition;
• 99≤Complex modulus E* after water-wet and dehydrated/Complex modulus E* before water-wet×100≤100 2.
• wherein E* represents the E* at 23° C. of the rubber composition;
• 99≤Volume when water-wet/Volume before water-wet×100≤100 3.
• wherein Volume represents the volume at 23° C. of the rubber composition;
• and
• wherein the rubber composition comprises carbon black, the carbon black being present in an amount of 5 parts by mass or less per 100 parts by mass of the rubber components.