I know what the size numbers mean IE 160/60/17 = 160mm wide aspect ratio 60% 17" rim. My question is this; I have also seen 160/55/17 tires. What is the advantage/disadvantage of a different aspect ratio. Does it have to do with the profile? Round vs more triangular?

:DI prefer round tires-They ride much better:D

:DI prefer round tires-They ride much better:D

...he'll be here all week. Try the veal...

Sorry, had nothing intelligent to say and couldnt pass it up!!LOL:)

Smaller sidewall height, so the tire is a smaller diameter. My guess is that'd increase speedo discrepancy even more in the positive direction.

As far as handling goes, I'd think a shorter sidewall would be stiffer but I haven't the foggiest as to what that means in the real world.

I know what the size numbers mean IE 160/60/17 = 160mm wide aspect ratio 60% 17" rim. My question is this; I have also seen 160/55/17 tires. What is the advantage/disadvantage of a different aspect ratio. Does it have to do with the profile? Round vs more triangular?

160/55-17 is not a standard size, could it have been a race tire?

Anyway, yes as mentioned above, a smaller aspect ratio makes the overall circumference smaller, but that is not the reason lower profile tires are used. With a lower profile you get more sidewall rigidity - the tire deforms less under cornering force, keeps a more consistent footprint on the ground, allows less lateral movement of the bike under that cornering force and that results in a more consistent feedback. Of course, it's more noticeable on racetracks than on your average Sunday ride, so I'm not sure you'll get any real benefit for street riding if you used such a tire.


Gustavo