I am looking to buy a used bike to get back into riding. I just found some great trails near my house that are hard packed stone dust. I would also like to be able to do some riding on roads also. Therefore decided to look for a hybrid. Found a great deal on a 2003 Specialized Sirrus. Evidently, the owner just replaced the tires with 700 x 25 tires for a road ride last month. Will these tires work ok on the trails or will I need to replace with something wider. If I need to replace, what would you suggest for this purpose and what will fit on the Sirrus?