There is a permanently signed cycle route around the IoW, it's the same route the IoW Randonnee follows and largely avoids the busier roads. It's signed in both directions (clockwise/anti-clockwise) with different colours (see here) so it's really easy to follow, and takes you through plenty of towns/villages so you're never too far away from a food/beer stop.
It's all on roads so shouldn't be any gravel unless there has been heavy rainfall to wash some into the road. I did it a few years back on 23c tyres so 28 should be fine!
There is a permanently signed cycle route around the IoW, it's the same route the IoW Randonnee follows and largely avoids the busier roads. It's signed in both directions (clockwise/anti-clockwise) with different colours (see here) so it's really easy to follow, and takes you through plenty of towns/villages so you're never too far away from a food/beer stop.