DougG

Are the sizes marked on tires, such as 2.1x26, an actual indication of the tire's width, or is it more complicated than that? The reason I ask is that I was in a shop browsing tires and saw that they had Continental Town & Country tires in two sizes that would probably fit my bike.

One set was 1.9x26 and the other was 2.1x26. Now if my math is correct, that's a difference of only .2 inches -- less than 1/4 inch. But the 2.1 clearly looked about half again as wide as the 1.9! It was definitely much wider than the size rating value would indicate.

So are tire sizes more an indication of something like a "size class" rather than indicating the actual width of the tire?

jezmellors

I'm speculating here but, a tyre cross-section being roughly circular, an increase in width would mean an increase in every direction at once and would give the appearance of much more tyre when off the bike. Either way, my understanding of it is that the measurement refers to the tyres width when inflated.

Wogster

In theory, when a tire is mounted and inflated to the optimum pressure it should be the marked width at the widest point, with no load. A tire that is on the rack at the LBS can appear a different size then it does when it's mounted and inflated. There is also variation in manufacturing, and some tires when measured are not the width indicated, because of marketing as well.

JanMM

Tire sizing info: https://sheldonbrown.com/tire-sizing.html

stapfam

Continental Town and Country are not a bad tyre. I used to use them in 1.5 size as a Mud tyre and as an occasional road tyre on the MTB. Seems funny to say that as the two would normally require a different tyre but the 1.5 size bit through the gloop to the hard surface below and the Tread gave grip on that. That same tread was Good as a Road tyre as it had plenty of rubber that was not aggressive knobblies to give grip on asphalt without causing drag.

But tyre size and a nominal 2.1 in one manufacturer will give a different actual size to another manufacturer. The actual size you use will depend on your usage- weight and terrain. The difference between a 1.9 and a 2.1 may not sound much but it can give different ride characteristics to the tyre. A narrower tyre will give better grip in Damp stuff and will be faster as it has less drag but it can give a big decrease in comfort. The narrow tyre can also give less grip on hard pack- roots or rock and will wear out faster.

I normally use a 1.8 tyre in the winter to give me better grip but cannot use them in the summer due to the hard- solid clay we have. The ride is too lumpy at speed on that stuff and vibrates the fillings.