Investing for Retirement

So I'm a small business owner and I'm 25 making 60k a year.

Currently have a Roth IRA.

As the future of the business is hard to predict, i'm having trouble allocating for retirement.

Would it be wise to split my money on roth and traditional? I currently only have a Roth open, but after thinking about it for awhile, diversification in account types seems appealing. We have no way to know what taxes will be like in 40 years, and my income future is hard to predict also (though common sense says it will go up).

TLDR: Roth, Traditional, OR BOTH? I'm leaning toward both