Thanks guys! Some things I found out reading about tires.Conti gp4000 and gatorskins are not designed to be ridden on gravel.Some tires are manufactured for a rider weight limit of 180 lbs. But I haven't noticed the weight limit listed on any sites yet.The S on conti gp4000s means silver lettering.It took me 60 seconds to buy 4 tires for my car and I have hours into these stupid bicycle tires.I'm now looking at Schwalbe marathon I like the idea of tread on a tire.