Ok I read and post here alot now we talk about wheel sets or what kinda of tire... But I never hear to much discussion on tire size. Right now I am running 28's. But I have been known to encounter gravel on my trips. What do you as a community think would be a ideal size for touring tires. I am talking all around, like gravel to road and so on. Then for a side banter, What kind of tread?
I would go up to 32's at least. The bigger tire is helpful on rough or slippery surfaces, the tread does not make much difference. We can only guess on an internet forum, It depends on your load and what the gravel road are like to really know. But I use smooth tread 32's with a load on dirt roads, but I go very carefully, and slowly. There are so many Kevlar belted tires now, don't leave out that feature.
I have used 32's mostly both Avocet slicks and Pasela with good effect. The only catch is deep pea gravel where the wheel tends to sink out of sight.....wider would be better there. I personally feel that 28s would be a bit of trouble. (I am 190#...so wider may be more of a neccessity for me!)
I have both of these & they do GREAT! The Marathons are 700 x 35c on a fendered Trek 520 (biggest that'll fit) & the Hurricanes are 26 x 1.75 on a mountain bike with out fenders, on or off road they each are very stable with a load. The Hurricanes are quite quiet runners, but are ready to "dig in" at any time.
Keep in mind that the larger the tire size, the slower your steering will be, due to the width and added trail that results from the height of the tire. I had some Nimbus Armadillos in a 700 x 38 width on my 520 last year when I was up in Oregon and riding on a fair number of dirt and gravel roads. They are a great tire, but I was shocked at how much lighter and quicker my steering was this summer when I went back to a Conti TT 700 x 32 on the 520, which is a somewhat slow-steering bike to begin with. I'm going to use the 38's on my hybrid instead, which steers fine with bigger tires. The Armadillo is a great tire but for a normal road bike or touring bike I would not go bigger than 32.
28's are usually considered to be short touring trip tires and carrying less weight on the bike. The bigger tires will handle heavier loaded bikes better as well as absorb road shock and last longer and handle gravel better. The 32 or 38 would be more suited for fully loaded touring. I ride on gravel with 25's everyonce in awhile with no problems...BUT the bike is not loaded; you load up a bike with another 60 pounds or so then riding on gravel with narrow tires could get tricky. What's worse then gravel for narrow tires is loose sand. I use to live in the Mojave desert area of Calif and everyonce in while had to ride on a sandy road or shoulder and the narrow tires would just cut into the sand causing you to fall off if your not careful; most of the time loose sand is all but impossible to ride on with narrower tires.