I am alos not sure whether it would increase your premium or not, but not telling them gives them the get out they need when you claim, and they don't want to pay you.
telling them does not mean they will charge more. After all, you may have had to change wheels due to a bit of kerb damage, which you decided you didn't want to claim on insurnace for. Replacing may have been cheaper than repair kind of thing?
And you also have the option, if they wish to increase premiums, to move to a different insurance company who may be cheaper anyway.
I would tell them.