that small of a change i wouldnt think any gearing needs changing. im running 33x12.5 and mine cruises fine on the freeway. check out randy's ring and pinion, they have a calculator to determine how far off your final gearing is from stock now. what year is your cruiser?
It would be a waste of both time and money to replace gears for such a minor change in tire size. I jumped from 32" tires to 35" tires on my 75 cruiser without changing gears. But I have the 4.11 ring and pinions. So my advice is to keep it as is.