As noted, the "700" refers to the rim diameter which is actually 622 mm across the bead seats. The 35 and 28 refer to the tire width, also in mm, so a 700x28 tire has a beadseat diameter of 622 mm and is 28 mm wide when installed. If you look on the tire side wall you should see the numbers 622-28 or 28-622. Any tire labeled 622 will fit your rims unless it is extremely narrow or extremely wide. Neither 28 nor 35 are a problem and you could exchange the 28 mm tires on your new wheel with the 35 mm tires on your old wheel if you wish.