Dave, nothing I have talks about it. Basically just 40# live loads. Try a search and email to places like jacuzzi and other manufacturers and post back with the results.
We just answered a similar question a while back but it was a same size tub. Sistering of joists across the span and bridging between them under tub should double the support and generally do it though. The closer to the end of the joist span (as opposed to being in the middle) the better support you will have. If over a crawlspace, then put in a couple concrete footings and piers. If over a basement, then a support pole or two may do it.