Tandem Cycling - touring tires? heavy load!!

I've searched for threads, on the subject but they don't meet our needs.
Planning a cross country tour on a tandem ( DaVinci) with my 80 pound son as stoker and me on the front. No trailer, fully self supported, and I'm huge. Looking at a total weight of riders, gear(70 lbs) bike is around 450 pounds.
The bikes can handle the load, trusting the builder on this, 26 inch wheels, now I need tires that can handle the load and bike trails (C&O canal, rails to trails etc..), and open road. We have looked at both the schwable marathon tour plus and the conti tour plus. We'd like to avoid flats as much as possible. Any others or other advice. Looking at the 1.75 inch or maybe even the 2.0, but that seems to be overkill?
Thanks for the wisdom and advice,

Rob

I don't know much about 26" tires. What has helped us more than anything in the "puncture vine heaven" of Central California is tire liners. That, and inspection of tires at every rest stop to check for potential problems.

I've had great success with tires made with kevlar or similar puncture resistant casings. Continental Gatorskins are know for their durability, but I don't know if they come in 26". I would think adding a set of self sealing inner tubes would be helpful, and since your load is already heavy, the few extra ounces should be no big deal.

I found these three which includes a Continental in a 26". Pricey at $65, but probably worth the investment if you plan to pedal across the country. Will you end up in New England?
http://www.bicycletires.com/bicycle_tires.asp#

Specialized Nimbus Armadillos or one of the other Amadillos with more tread would be perfect. I have only had one flat with my Armadillos, and it was from an industrial staple that I didn't see in the road. Thousands of miles since then with no flats. I run them on my touring and my tandem bikes.

Thanks for the advice, the Conti Top contact looks interesting, I 'll check with my LBS. What do you folks think of boosting the pressure past the side wall reccomendation?
I'll take a look at the Specialized, as for liners I'm torn gotten a lot of advice against.
New England isn't in the cards, we are starting in Washington DC, my wife and I met in the tri state area, WV,VA,MD. she was born and raised I was a transplant. We want to show or 8 and 10 year where we came from. From there the canal/GAP and home to WA state by the northern teir &trails

What do you folks think of boosting the pressure past the side wall reccomendation?


For years and years I have run tires that specified 120 PSI on the sidewall at 130 PSI. Never had a problem. Seemed to have fewer flats.

We have good luck with the Schwalbe Marathon Racers in th 26 x 1.5" size. They are flat resistent, long wearing and have held up in the three years that we have had our Mocha.
Sheldon