First off, I"m an uber clyde @ 390 lbs and I'm converting an old trek 850 mountain bike for riding on asphalt / concrete. I've read many threads that suggest changing the mountain bike tires to HIGH PRESSURE SLICKS. The question is, at my weight, what tire pressure is considered high for a 26 inch wheel? Some suggest skinny high pressure tires such as 1.5 width, again will this do at my weight. Any input would be greatly appreciated.