<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-12-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001166789</issuerCik>
        <issuerName>LIN TV CORP.</issuerName>
        <issuerTradingSymbol>TVL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001213043</rptOwnerCik>
            <rptOwnerName>BANOWSKY WILLIAM S JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1614 WEST FIFTH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>AUSTIN</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>78703</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock (Restricted Shares)</value>
            </securityTitle>
            <transactionDate>
                <value>2011-12-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>14200</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>108661</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Restricted shares were awarded pursuant to the amended and restated 2002 Non-Employee Director Stock Plan. The shares are subject to forfeiture and are non-transferable until vested. The shares vest in three (3) annual installments from the date of grant. Twenty five percent (25%) of the shares vest upon the first and second anniversary, the remaining fifty percent (50%) vests on the third anniversary of the date of grant.</footnote>
        <footnote id="F2">This number includes 52,178 restricted shares awarded pursuant to the amended and restated 2002 Non-Employee Director Stock Plan. These shares remain subject to forfeiture and are nontransferable until vested. The shares vest over either three (3), four (4) or five (5) years from the date of grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Nicholas N. Mohamed, Attorney-in-fact for William S. Banowsky, Jr.</signatureName>
        <signatureDate>2011-12-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
