I am looking to buy a Cross bike, first to ride, then maybe compete. I am currently a Clyde in the 275 pound area and was wondering if any of you at this size ride and more specifically if you have any problems with tire pressure. I have been trying out a bike, and making sure to keep the tires fully inflated, but I can't help but think that the rear tire looks a little low at times. Any thoughts or input. I don't want to necessarily be stuck with thicker tires as I ride a lot on streets, with only some paths.