mere speculation
DavidF,
Why would an Ohio dealer Ship your bike with a 30-day tag?
When motorcycle dealers transfer stock among themselves (across state lines) they ship the product only. All motorcycle products arrive at dealers with an MSO (Manufacturer Statement of Origin) certificate that launches the registration process once a retail buyer (that's us) signs a state motor vehicle form at purchase time. The vehicle registration form gets sent off to the state along with the MSO in order that state title transfers are tracked from then on.
What I'm saying is that the Ohio dealer could have sent you the Burgman without a temporary tag that you'll have to register into your state in order to operate the bike in your state.
Without a valid Ohio state address to accompany the Ohio tag, I don't know how a Washington state insurer will assign a Binder to cover the Burgman into Washington state if you ride the temporary tagged Burgman.
As for taxation on the sale of the bike in Ohio, you should not be obligated to pay Washington state any tax. Also, you may only be obligated to pay Ohio state tax and not a tabled percent as an Ohio buyer would if they bought the same bike as an Ohio resident.
Many dealers rubber stamp tax calculations onto Purchase Agreement forms regardless of variations in state tax recovery that an out of state buyer would ultimately pay less for.
Check Ohio's website to see if the bike would be taxed as used because you, the buyer, would not use it until it had a title transfer into your state.
This could reflect a few hundred bucks.
Carrying the MSO into your state's vehicles office instead of an out of state registration/title transfer could also save you dough in terms of duplicated fee payments you've made into two states.
If you're stuck with a Purchase Agreement that has already been signed plus tendered in full, ask Ohio for tax forms to recover the overpaid tax percentages back to you with a check.