Train between Florence and Pisa can't book more than 6 weeks ahead?

The only trains on that route are regionale, which can only be bought a week in advance. Don't worry, you can easily buy once you are in Italy, there are plenty of trains available every hour and they don't sell out.

Okay Thanks

The trains between Florence and Pisa are regionale trains. Trenitalia will not sell regionale tickets online more than 7 days out from the time of travel. Not a problem. You can easily buy the tickets at the Florence SMN train station, validate the tickets and get on the train. No seat reservations on the regionale trains. They can't be sold out either as you can stand if there are no seats. Not to worry here either. The train runs originate in Florence so the trains are empty. Lastly, if you buy the tickets for regionale trains in Italy, the tickets are good for 60 days. Once you validate them, you must complete your journey in 4 hours. If you purchase online, your tickets will be pre-validated but you lose the nice 60 day window. You have to use the ticket within a 4 hour window of the pre-validate time on the ticket. Very easy to buy these tickets in Italy. With the 60 day window, you can purchase 1-2 days in advance and use them when you need them.

Larry didn't say it but for the reasons he listed you should NEVER buy regionale train tickets on line.

I can add that if you are considering buying tickets from RailEurope, at least go to www.Trenitalia.com and compare costs and options. RailEurope does make it easy for someone in the US to buy tickets, but usually offers premium trains and at prices to match. It never hurts to compare.

Of course for the Florence/Pisa leg is not an issue, but as an example, on a date out in June tickets from Florence to Venice on Raileurope are going for a minimum of 67 USD, on Trenitalia about 40 USD. Another option is to look at Italo, a newer train service, limited routes, but competitive.