Yeah, going from a 150 to a 160 isn't going to improve handling, but it won't make that much of a difference. Though, what are you after? A fatter looking back tyre? Nobody is going to notice the difference between a 15cm skinny ass tyre and a 16cm skinny ass tyre!

Just be happy you don't have an NSR150 with an anorexic skinny ass rear tyre!

Putting a wider tyre can often reduce the roundness, making the tyre more square. Now that can't be good on corners.

Remember, form follows function. Paraphrased - function first, then appearance.