If the amount in your traditional IRAs exceeds your basis in nondeductible traditional IRA contributions as is apparently presently the case, some portion of your Roth conversion will be taxable.
Traditional IRAs are not segregated between earnings and other amounts. Traditional IRAs simply contain some Fair Market Value (total balance) and some amount of nondeductible contributions. Perhaps your balance happens to exceeds your basis by the amount of earnings in a particular IRA account, but that's not really relevant. It doesn't matter how the amount that is in excess of your basis came to be in your IRAs, whether it be from investment gains or from deductible contributions. The amount that is in excess of your basis is taxable when distributed (and not rolled over) or converted to Roth.
