john,
on the recommendation of another member here... a few years back i went to
Bennett Street Tire & Glass
(781) 598-1613
60 Bennett St
Lynn, MA 01905
http://www.bennettstreettireglass.com
to get some new michelins for my former sand sled.
you couldn't beat their prices.
a bit out of the way, but, IIRC, even with the drive and time factored in (you know where I live), it was well worth the trip for me.
give 'em a call ... they are good at quoting prices over the phone.