In your experience, what tube stands up to hard use and lasts several seasons? My boys are 180 lbs, 200 lbs., and 240 lbs. This season we have gone through two tubes. I patched one, but it did not last. The West Marine sale flier arrived today so got me thinking now is the time to buy replacements. We like the flat kind on which you lie down. Definitely don't like the donut type. If there are other styles, we have not tried them. Recommendations for a well-made, long-lasting tube appreciated. If you can recommend a retail source, that would be helpful, too. We live in the Chicago area. Thanks.