Selecting a tire width for touring is where folks differ and this is mostly due to what the rider feels comfortable with in terms of performance and handling over their most traveled surface. Another consideration is how much stuff gets packed into panniers which is another consideration for wheel stress. Some touring tires bear the weight of loaded racks and panniers better than others. When I rode with Schwalbe Marathon tires in the 700 x 32 size it felt as though the tires provided suspension between the road surface and the wheel's rims. However with the same tire in the 28mm width the ride was so harsh that I was regularly having to true the rear wheel. As the tire's casing was so robust and solid though hardly wider than my Velocity Dyad touring rims the tires seemed to echo every rough surface reverberating to my hands. Over rough asphalt it was tolerable but over gravel and dirt roads was when the wheels took most of the beating. Sure I never ever got a flat with those tires even when I rolled over a patch of goat head thorns for a quarter mile or so that had accumulated on the tire to the point where they were scraping on my fenders. I still didn't get a flat!
I currently own a pair of very robust Vittoria Randonneur Touring tires with their Ultra Shield flat protection. They are thick, heavy tires that require a bit of pushing on most rides. Over gravel roads or trails they are exemplary with more tread depth than my Schwalbe Marathons and really seem to roll faster on or off road. It is also the widest tire I have ever installed on my road touring bike at 35mm and they just barely clear the full fenders. When I ride over very loose gravel or rocks I can often hear the tires throwing debris around under the fenders. During fall wet weather riding some times wet or partially wet leaves would get stuck in the narrow clearance between the tire and fender.
There is a brick and cobblestone pathway near our house that is perfect for testing how a tire feels over an irregular surface. It's not so much that it's bumpy it's that some tires actually feel that they grab and drop into each perpendicular groove between the bricks and rocks along the path which can feel very disconcerting. Even the robust size of the Vittoria's felt that way and I attribute it more to the tread design than anything else as it is designed to handle loose stuff with dirt and gravel.
While packing my panniers for a regional bike tour I mindlessly tossed a Panaracer Pasela Tour Guard folding bead 700 x 32 tire that I have kept either in a pannier as a spare for long tours or in a tool box when not needed. I rode with these tires more than ten years ago on an old mountain bike I used for commuting. I remembered how fast those tires rolled although other tires offered better flat protection. I decided to order a second tire to match my old spare to see how I would like the ride.
First thing I did was "hit the bricks" with them as previously mentioned and the Paselas rolled over all those grooves like they weren't even there. Not once did the tires grab or get hung up in the grooves along the surface, not even in the curve where tires that don't perform well or perform even reasonably well always seem to grab. Next I took the tires for a fifteen mile jaunt as the wind was kicking up pretty good and set a course that would best challenge the rolling resistance, or lack of resistance of the tires. As with any tire review I simply fill the tire to the manufacturer's recommended pressure. For the Pasela TG's it's ninety five, same as my old Schwalbe Marathons and both tires are made of 66 tpi whereas the Vittoria's are 30 tpi and run at seventy psi. Weight differences are 640 grams for the Schwalbe Marathon 700 x 32 and 360 grams for the Pasela Tour Guard in the same size. Schwalbe has added a disclaimer stating that their flat protection technology does not increase rolling resistance, I'm sure that's true but the weight difference of the tires is significant enough to be noticeable. I say this after having swapped the Vittoria's which weigh in at 760 grams, which is twice the weight of of the Paselas.
This summer I am going to enjoy riding these tires for increased speed on hot days and high winds. When I feel the need to pack a lot of stuff for full touring rides I will use the Vittoria's for extra girth and added flat protection. For everyday commuting in areas of broken glass and regular road hazard debris the Paselas are an excellent choice. This is an excellent light weight fast rolling tire for bike commuting or touring .
Links related to this topic:
Vittoria Touring Tire review
Best Budget Tires for Bike Commuting
Favorite Gravel Grinding Tires